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useState(true);
HOW THE USEEFFECT HOOK WORKS (WITH EXAMPLES) How the useEffect Hook Works (with Examples) The useEffect hook is the Swiss Army knife of all the hooks. It’s the solution to many problems: how to fetch data when a component mounts, how to run code when state changes or when a prop changes, how to set up timers or intervals, you name it. Pretty much anything you want to “do” in aReact
STATE OF THE REACT ECOSYSTEM IN 2021 The core skill of “thinking in React” hasn’t changed much at all over the years. It’s still all about one-way data flow, props, state, and JSX. Things like being able to break a design into components are still crucial, as is deciding which components should “own” data and which should merely display it. I REACT STATE MANAGEMENT LIBRARIES AND HOW TO CHOOSE React State Management Libraries and How to Choose. The idea of state is one of the trickier things to nail down when you’re starting with React, and as your app grows, so do your state management needs. In this post I’ll give you the Grand Tour of state management options in React and help you decide which one to use in your project. REACT USECONTEXT HOOK TUTORIAL (WITH EXAMPLES) React Consumer example on CodeSandbox.. First, we create a new context, which we store in NumberContext.This is an object with 2 properties: Provider and Consumer.They’re a matched pair, and they’re born knowing how to communicate with each other (but not with other contexts). REDUX SELECTORS: A QUICK TUTORIAL In our made-up example, it’s keeping track of the logged-in user, the products in your shop, and the items in the user’s shopping cart. The data here is normalized, so items in the shopping cart are referenced by ID.When a user adds an item to their cart, the item itself is not copied into the cart – only the item’s ID gets added to the shoppingCart.itemIds array. WHEN TO USELAYOUTEFFECT INSTEAD OF USEEFFECT (EXAMPLE) When to useLayoutEffect. The right time to useLayoutEffect instead? You’ll know it when you see it. Literally ;) If your component is flickering when state is updated – as in, it renders in a partially-ready state first and then immediately re-renders in its final state – that’s a good clue that it’s time to swap in useLayoutEffect.. This’ll be the case when your update is a 2-step ACCESS THE REDUX STORE OUTSIDE A REACT COMPONENT Option 4: Pass the Value From a React Component. It’s simple to get access to the store inside a React component – no need to pass the store as a prop or import it, just use the connect function from React Redux, and supply a mapStateToProps function that pulls out the data you need. Then, inside the component, you can pass that data to a USING REACT IN MULTIPLE ENVIRONMENTS Configure Endpoints at Build Time. If you’d rather configure the API endpoints at build time, that works too. If you’re using Create React App, then you’ll have a global process.env available to get access to environment variables, including process.env.NODE_ENV, which will be set to “production” after a build.. Additionally, Create React App will only have access to environment HOW TO READ REACT ERRORS (FIX 'CANNOT READ PROPERTY OF Cannot read property means the code was trying to read a property. This is a good clue! There are only a few ways to read properties in JavaScript. The most common is probably the . operator. As in user.name, to access the name property of the user object. Or items.map, to access the map property of the items object. MODAL DIALOGS IN REACT When the App component first renders, its isOpen state is false, so the Modal is not rendered.. this. state = {isOpen: false};. Then when the user clicks the “Open the modal” button, it calls toggleModal which flips that flag to true.. toggleModal = => {this. setState ({isOpen:! this. state. isOpen});}. The setState call triggers a re-render, and now Modal gets passed show={true}, so it COMPUTED PROPERTIES IN REACT React doesn’t have “computed properties” but you can achieve the same effect with functions. If the computation is short and quick, do it in render (or directly in a function component) If the computation is complex to read or needs to be reused, extract it to a function. If the computation is expensive to run, consider memoizing it. STATE OF THE REACT ECOSYSTEM IN 2021 The core skill of “thinking in React” hasn’t changed much at all over the years. It’s still all about one-way data flow, props, state, and JSX. Things like being able to break a design into components are still crucial, as is deciding which components should “own” data and which should merely display it. I REACT STATE MANAGEMENT LIBRARIES AND HOW TO CHOOSE React State Management Libraries and How to Choose. The idea of state is one of the trickier things to nail down when you’re starting with React, and as your app grows, so do your state management needs. In this post I’ll give you the Grand Tour of state management options in React and help you decide which one to use in your project. REACT USECONTEXT HOOK TUTORIAL (WITH EXAMPLES) React Consumer example on CodeSandbox.. First, we create a new context, which we store in NumberContext.This is an object with 2 properties: Provider and Consumer.They’re a matched pair, and they’re born knowing how to communicate with each other (but not with other contexts). REDUX SELECTORS: A QUICK TUTORIAL In our made-up example, it’s keeping track of the logged-in user, the products in your shop, and the items in the user’s shopping cart. The data here is normalized, so items in the shopping cart are referenced by ID.When a user adds an item to their cart, the item itself is not copied into the cart – only the item’s ID gets added to the shoppingCart.itemIds array. WHEN TO USELAYOUTEFFECT INSTEAD OF USEEFFECT (EXAMPLE) When to useLayoutEffect. The right time to useLayoutEffect instead? You’ll know it when you see it. Literally ;) If your component is flickering when state is updated – as in, it renders in a partially-ready state first and then immediately re-renders in its final state – that’s a good clue that it’s time to swap in useLayoutEffect.. This’ll be the case when your update is a 2-step ACCESS THE REDUX STORE OUTSIDE A REACT COMPONENT Option 4: Pass the Value From a React Component. It’s simple to get access to the store inside a React component – no need to pass the store as a prop or import it, just use the connect function from React Redux, and supply a mapStateToProps function that pulls out the data you need. Then, inside the component, you can pass that data to a USING REACT IN MULTIPLE ENVIRONMENTS Configure Endpoints at Build Time. If you’d rather configure the API endpoints at build time, that works too. If you’re using Create React App, then you’ll have a global process.env available to get access to environment variables, including process.env.NODE_ENV, which will be set to “production” after a build.. Additionally, Create React App will only have access to environment HOW TO READ REACT ERRORS (FIX 'CANNOT READ PROPERTY OF Cannot read property means the code was trying to read a property. This is a good clue! There are only a few ways to read properties in JavaScript. The most common is probably the . operator. As in user.name, to access the name property of the user object. Or items.map, to access the map property of the items object. MODAL DIALOGS IN REACT When the App component first renders, its isOpen state is false, so the Modal is not rendered.. this. state = {isOpen: false};. Then when the user clicks the “Open the modal” button, it calls toggleModal which flips that flag to true.. toggleModal = => {this. setState ({isOpen:! this. state. isOpen});}. The setState call triggers a re-render, and now Modal gets passed show={true}, so it COMPUTED PROPERTIES IN REACT React doesn’t have “computed properties” but you can achieve the same effect with functions. If the computation is short and quick, do it in render (or directly in a function component) If the computation is complex to read or needs to be reused, extract it to a function. If the computation is expensive to run, consider memoizing it. STATE OF THE REACT ECOSYSTEM IN 2021 The core skill of “thinking in React” hasn’t changed much at all over the years. It’s still all about one-way data flow, props, state, and JSX. Things like being able to break a design into components are still crucial, as is deciding which components should “own” data and which should merely display it. I USING REACT IN MULTIPLE ENVIRONMENTS Configure Endpoints at Build Time. If you’d rather configure the API endpoints at build time, that works too. If you’re using Create React App, then you’ll have a global process.env available to get access to environment variables, including process.env.NODE_ENV, which will be set to “production” after a build.. Additionally, Create React App will only have access to environment REACT HOOK TO RUN CODE AFTER RENDER Can you run a hook before render? The short answer is no, not really.useEffect is the only hook that is meant for tying in to the component lifecycle, and it only ever runs after render. (useLayoutEffect is the same, it also runs after render).The longer answer is that technically, a React hook is just a function. And you could write a custom hook that’ll run before the component returns COMPUTED PROPERTIES IN REACT React doesn’t have “computed properties” but you can achieve the same effect with functions. If the computation is short and quick, do it in render (or directly in a function component) If the computation is complex to read or needs to be reused, extract it to a function. If the computation is expensive to run, consider memoizing it. MODAL DIALOGS IN REACT So that’s what’s happening: when the “Close” button is clicked, it calls the onClose prop – which is, in fact, the toggleModal function in App.That function flips the isOpen flag, which triggers a re-render, and the modal disappears. It’s truly gone, too: try a right-click “Inspect Element” while the modal is closed and you will notice the modal is nowhere to be found in the DOM. CREATE REACT APP WITH AN EXPRESS BACKEND If you haven’t heard of it yet, Create React App is an awesome way to get started with React. It creates a project structure for you, all set up and ready to go. You get to skip the configuration of Webpack and Babel, and get right down to writing your app. WHERE TO INITIALIZE STATE IN REACT So, is it ever ok to initialize state based on props? Yes. The original version of the React docs mentioned this: However, it’s not an anti-pattern if you make it clear that the prop is only seed data for the component’s internally-controlled state. DEPLOY A PROJECT TO YOUR SERVER WITH GIT So you’ve got a local git repository, and you want to deploy it to your own server. Maybe the repo is kept in GitHub, maybe not. Maybe your server is on DigitalOcean, or AWS, or 4 EXAMPLES OF THE USESTATE HOOK useState returns an array with 2 elements, and we’re using ES6 destructuring to assign names to them. The first element is the current value of the state, and the second element is a state setter function – just call it with a new value, and the state will be set and the component will re-render. const =useState(true);
HOW THE USEEFFECT HOOK WORKS (WITH EXAMPLES) How the useEffect Hook Works (with Examples) The useEffect hook is the Swiss Army knife of all the hooks. It’s the solution to many problems: how to fetch data when a component mounts, how to run code when state changes or when a prop changes, how to set up timers or intervals, you name it. Pretty much anything you want to “do” in aReact
REACT USECONTEXT HOOK TUTORIAL (WITH EXAMPLES) React Consumer example on CodeSandbox.. First, we create a new context, which we store in NumberContext.This is an object with 2 properties: Provider and Consumer.They’re a matched pair, and they’re born knowing how to communicate with each other (but not with other contexts). STATE OF THE REACT ECOSYSTEM IN 2021 The core skill of “thinking in React” hasn’t changed much at all over the years. It’s still all about one-way data flow, props, state, and JSX. Things like being able to break a design into components are still crucial, as is deciding which components should “own” data and which should merely display it. I REACT STATE MANAGEMENT LIBRARIES AND HOW TO CHOOSE React State Management Libraries and How to Choose. The idea of state is one of the trickier things to nail down when you’re starting with React, and as your app grows, so do your state management needs. In this post I’ll give you the Grand Tour of state management options in React and help you decide which one to use in your project. ACCESS THE REDUX STORE OUTSIDE A REACT COMPONENT Option 4: Pass the Value From a React Component. It’s simple to get access to the store inside a React component – no need to pass the store as a prop or import it, just use the connect function from React Redux, and supply a mapStateToProps function that pulls out the data you need. Then, inside the component, you can pass that data to a REDUX SELECTORS: A QUICK TUTORIAL In our made-up example, it’s keeping track of the logged-in user, the products in your shop, and the items in the user’s shopping cart. The data here is normalized, so items in the shopping cart are referenced by ID.When a user adds an item to their cart, the item itself is not copied into the cart – only the item’s ID gets added to the shoppingCart.itemIds array. HOW TO READ REACT ERRORS (FIX 'CANNOT READ PROPERTY OF Cannot read property means the code was trying to read a property. This is a good clue! There are only a few ways to read properties in JavaScript. The most common is probably the . operator. As in user.name, to access the name property of the user object. Or items.map, to access the map property of the items object. REACT HOOK TO RUN CODE AFTER RENDER Can you run a hook before render? The short answer is no, not really.useEffect is the only hook that is meant for tying in to the component lifecycle, and it only ever runs after render. (useLayoutEffect is the same, it also runs after render).The longer answer is that technically, a React hook is just a function. And you could write a custom hook that’ll run before the component returns WHEN TO USELAYOUTEFFECT INSTEAD OF USEEFFECT (EXAMPLE) When to useLayoutEffect. The right time to useLayoutEffect instead? You’ll know it when you see it. Literally ;) If your component is flickering when state is updated – as in, it renders in a partially-ready state first and then immediately re-renders in its final state – that’s a good clue that it’s time to swap in useLayoutEffect.. This’ll be the case when your update is a 2-step MAKE YOUR OWN REACT CLI WITH BASH You can build your very own, with Bash and a couple lines of script. I’ll show you how in this post. Here’s what our CLI will do: create the component folder. add a barebones component file to the folder. add a blank SCSS file to the folder. include the SCSS in the component. If you’re on a system like Mac or Linux this is allpossible
DEPLOY A PROJECT TO YOUR SERVER WITH GIT So you’ve got a local git repository, and you want to deploy it to your own server. Maybe the repo is kept in GitHub, maybe not. Maybe your server is on DigitalOcean, REACT USECONTEXT HOOK TUTORIAL (WITH EXAMPLES) React Consumer example on CodeSandbox.. First, we create a new context, which we store in NumberContext.This is an object with 2 properties: Provider and Consumer.They’re a matched pair, and they’re born knowing how to communicate with each other (but not with other contexts). STATE OF THE REACT ECOSYSTEM IN 2021 The core skill of “thinking in React” hasn’t changed much at all over the years. It’s still all about one-way data flow, props, state, and JSX. Things like being able to break a design into components are still crucial, as is deciding which components should “own” data and which should merely display it. I REACT STATE MANAGEMENT LIBRARIES AND HOW TO CHOOSE React State Management Libraries and How to Choose. The idea of state is one of the trickier things to nail down when you’re starting with React, and as your app grows, so do your state management needs. In this post I’ll give you the Grand Tour of state management options in React and help you decide which one to use in your project. ACCESS THE REDUX STORE OUTSIDE A REACT COMPONENT Option 4: Pass the Value From a React Component. It’s simple to get access to the store inside a React component – no need to pass the store as a prop or import it, just use the connect function from React Redux, and supply a mapStateToProps function that pulls out the data you need. Then, inside the component, you can pass that data to a REDUX SELECTORS: A QUICK TUTORIAL In our made-up example, it’s keeping track of the logged-in user, the products in your shop, and the items in the user’s shopping cart. The data here is normalized, so items in the shopping cart are referenced by ID.When a user adds an item to their cart, the item itself is not copied into the cart – only the item’s ID gets added to the shoppingCart.itemIds array. HOW TO READ REACT ERRORS (FIX 'CANNOT READ PROPERTY OF Cannot read property means the code was trying to read a property. This is a good clue! There are only a few ways to read properties in JavaScript. The most common is probably the . operator. As in user.name, to access the name property of the user object. Or items.map, to access the map property of the items object. REACT HOOK TO RUN CODE AFTER RENDER Can you run a hook before render? The short answer is no, not really.useEffect is the only hook that is meant for tying in to the component lifecycle, and it only ever runs after render. (useLayoutEffect is the same, it also runs after render).The longer answer is that technically, a React hook is just a function. And you could write a custom hook that’ll run before the component returns WHEN TO USELAYOUTEFFECT INSTEAD OF USEEFFECT (EXAMPLE) When to useLayoutEffect. The right time to useLayoutEffect instead? You’ll know it when you see it. Literally ;) If your component is flickering when state is updated – as in, it renders in a partially-ready state first and then immediately re-renders in its final state – that’s a good clue that it’s time to swap in useLayoutEffect.. This’ll be the case when your update is a 2-step MAKE YOUR OWN REACT CLI WITH BASH You can build your very own, with Bash and a couple lines of script. I’ll show you how in this post. Here’s what our CLI will do: create the component folder. add a barebones component file to the folder. add a blank SCSS file to the folder. include the SCSS in the component. If you’re on a system like Mac or Linux this is allpossible
DEPLOY A PROJECT TO YOUR SERVER WITH GIT So you’ve got a local git repository, and you want to deploy it to your own server. Maybe the repo is kept in GitHub, maybe not. Maybe your server is on DigitalOcean, REDUX SELECTORS: A QUICK TUTORIAL In our made-up example, it’s keeping track of the logged-in user, the products in your shop, and the items in the user’s shopping cart. The data here is normalized, so items in the shopping cart are referenced by ID.When a user adds an item to their cart, the item itself is not copied into the cart – only the item’s ID gets added to the shoppingCart.itemIds array. HOW TO STRUCTURE YOUR REACT PROJECT Redux. If your current level of comfort with React leads you to read articles about how to best organize your project, you probably do notneed Redux yet.
HOW REDUX WORKS: A COUNTER-EXAMPLE Create a src/Counter.js with the code from the Counter example above.; On to the React Redux Example. As discussed in Part 1, Redux keeps the state of your app in a single store.Then, you can extract parts of that state and plug it into your components as props. This lets you keep data in one global place (the store) and feed it directly to any component in the app, without the gymnastics of COMPUTED PROPERTIES IN REACT React doesn’t have “computed properties” but you can achieve the same effect with functions. If the computation is short and quick, do it in render (or directly in a function component) If the computation is complex to read or needs to be reused, extract it to a function. If the computation is expensive to run, consider memoizing it. USING THE IMAGE TAG IN REACT Option 1: import the image into the component. Put the image file somewhere under the src folder. This alone will not automatically make it available, so you have to import the image into the React component where you’re using it. import companyLogo from './path/to/logo.jpg';Then you
RUN CODE IN REACT BEFORE RENDER Initializing state actually does run before the first render, and leaving it uninitialized is a common source of problems. This leads to errors like Cannot read property 'map' of undefined' when the component tries to render before the data is ready. If you have a call like useState () with nothing between the parens, that’suninitialized (it
CREATE REACT APP WITH AN EXPRESS BACKEND If you haven’t heard of it yet, Create React App is an awesome way to get started with React. It creates a project structure for you, all set up and ready to go. You get to skip the configuration of Webpack and Babel, and get right down to writing your app. WHERE TO INITIALIZE STATE IN REACT Directly Inside the Class. The second way to initialize state is directly inside the class definition, using a class property. Here’s what that looks like: class App extends React.Component { state = { loggedIn: false, currentState: "not-panic", someDefaultThing: this.props.whatever } render() { // whatever you like } } REACT APP NOT WORKING? 4 QUICK DEBUGGING TIPS Check the dev server console - If you’re running Webpack’s dev server (or using Create React App or a similar tool), look at that terminal window for clues. Syntax errors will break the compiler, which means your changes will not appear until you fix those errors. Refresh the page - Manually refresh the page. Hit Cmd + Shift + R(Mac) or
HOW THE USEEFFECT HOOK WORKS (WITH EXAMPLES) How the useEffect Hook Works (with Examples) The useEffect hook is the Swiss Army knife of all the hooks. It’s the solution to many problems: how to fetch data when a component mounts, how to run code when state changes or when a prop changes, how to set up timers or intervals, you name it. Pretty much anything you want to “do” in aReact
REACT USECONTEXT HOOK TUTORIAL (WITH EXAMPLES) React Consumer example on CodeSandbox.. First, we create a new context, which we store in NumberContext.This is an object with 2 properties: Provider and Consumer.They’re a matched pair, and they’re born knowing how to communicate with each other (but not with other contexts). REDUX SELECTORS: A QUICK TUTORIAL In our made-up example, it’s keeping track of the logged-in user, the products in your shop, and the items in the user’s shopping cart. The data here is normalized, so items in the shopping cart are referenced by ID.When a user adds an item to their cart, the item itself is not copied into the cart – only the item’s ID gets added to the shoppingCart.itemIds array. REACT STATE MANAGEMENT LIBRARIES AND HOW TO CHOOSE React State Management Libraries and How to Choose. The idea of state is one of the trickier things to nail down when you’re starting with React, and as your app grows, so do your state management needs. In this post I’ll give you the Grand Tour of state management options in React and help you decide which one to use in your project. HOW TO STRUCTURE YOUR REACT PROJECT HOW REDUX WORKS: A COUNTER-EXAMPLE Create a src/Counter.js with the code from the Counter example above.; On to the React Redux Example. As discussed in Part 1, Redux keeps the state of your app in a single store.Then, you can extract parts of that state and plug it into your components as props. This lets you keep data in one global place (the store) and feed it directly to any component in the app, without the gymnastics of ACCESS THE REDUX STORE OUTSIDE A REACT COMPONENT Option 4: Pass the Value From a React Component. It’s simple to get access to the store inside a React component – no need to pass the store as a prop or import it, just use the connect function from React Redux, and supply a mapStateToProps function that pulls out the data you need. Then, inside the component, you can pass that data to a WHEN TO USELAYOUTEFFECT INSTEAD OF USEEFFECT (EXAMPLE) When to useLayoutEffect. The right time to useLayoutEffect instead? You’ll know it when you see it. Literally ;) If your component is flickering when state is updated – as in, it renders in a partially-ready state first and then immediately re-renders in its final state – that’s a good clue that it’s time to swap in useLayoutEffect.. This’ll be the case when your update is a 2-step USING REACT IN MULTIPLE ENVIRONMENTS Configure Endpoints at Build Time. If you’d rather configure the API endpoints at build time, that works too. If you’re using Create React App, then you’ll have a global process.env available to get access to environment variables, including process.env.NODE_ENV, which will be set to “production” after a build.. Additionally, Create React App will only have access to environment 4 EXAMPLES OF THE USESTATE HOOK useState returns an array with 2 elements, and we’re using ES6 destructuring to assign names to them. The first element is the current value of the state, and the second element is a state setter function – just call it with a new value, and the state will be set and the component will re-render. const =useState(true);
DO I NEED NODE.JS IN THE BACKEND? I’ve seen a number of people asking this question, in a few different ways: My site is hosted on a PHP/MySQL backend and I read somewhere that I need to have a Node.js environment in the backend to use these new JavaScript libraries like React and Angular 2. REACT USECONTEXT HOOK TUTORIAL (WITH EXAMPLES) React Consumer example on CodeSandbox.. First, we create a new context, which we store in NumberContext.This is an object with 2 properties: Provider and Consumer.They’re a matched pair, and they’re born knowing how to communicate with each other (but not with other contexts). REDUX SELECTORS: A QUICK TUTORIAL In our made-up example, it’s keeping track of the logged-in user, the products in your shop, and the items in the user’s shopping cart. The data here is normalized, so items in the shopping cart are referenced by ID.When a user adds an item to their cart, the item itself is not copied into the cart – only the item’s ID gets added to the shoppingCart.itemIds array. REACT STATE MANAGEMENT LIBRARIES AND HOW TO CHOOSE React State Management Libraries and How to Choose. The idea of state is one of the trickier things to nail down when you’re starting with React, and as your app grows, so do your state management needs. In this post I’ll give you the Grand Tour of state management options in React and help you decide which one to use in your project. HOW TO STRUCTURE YOUR REACT PROJECT HOW REDUX WORKS: A COUNTER-EXAMPLE Create a src/Counter.js with the code from the Counter example above.; On to the React Redux Example. As discussed in Part 1, Redux keeps the state of your app in a single store.Then, you can extract parts of that state and plug it into your components as props. This lets you keep data in one global place (the store) and feed it directly to any component in the app, without the gymnastics of ACCESS THE REDUX STORE OUTSIDE A REACT COMPONENT Option 4: Pass the Value From a React Component. It’s simple to get access to the store inside a React component – no need to pass the store as a prop or import it, just use the connect function from React Redux, and supply a mapStateToProps function that pulls out the data you need. Then, inside the component, you can pass that data to a WHEN TO USELAYOUTEFFECT INSTEAD OF USEEFFECT (EXAMPLE) When to useLayoutEffect. The right time to useLayoutEffect instead? You’ll know it when you see it. Literally ;) If your component is flickering when state is updated – as in, it renders in a partially-ready state first and then immediately re-renders in its final state – that’s a good clue that it’s time to swap in useLayoutEffect.. This’ll be the case when your update is a 2-step USING REACT IN MULTIPLE ENVIRONMENTS Configure Endpoints at Build Time. If you’d rather configure the API endpoints at build time, that works too. If you’re using Create React App, then you’ll have a global process.env available to get access to environment variables, including process.env.NODE_ENV, which will be set to “production” after a build.. Additionally, Create React App will only have access to environment 4 EXAMPLES OF THE USESTATE HOOK useState returns an array with 2 elements, and we’re using ES6 destructuring to assign names to them. The first element is the current value of the state, and the second element is a state setter function – just call it with a new value, and the state will be set and the component will re-render. const =useState(true);
DO I NEED NODE.JS IN THE BACKEND? I’ve seen a number of people asking this question, in a few different ways: My site is hosted on a PHP/MySQL backend and I read somewhere that I need to have a Node.js environment in the backend to use these new JavaScript libraries like React and Angular 2. HOW REDUX WORKS: A COUNTER-EXAMPLE Create a src/Counter.js with the code from the Counter example above.; On to the React Redux Example. As discussed in Part 1, Redux keeps the state of your app in a single store.Then, you can extract parts of that state and plug it into your components as props. This lets you keep data in one global place (the store) and feed it directly to any component in the app, without the gymnastics of USING REACT IN MULTIPLE ENVIRONMENTS Configure Endpoints at Build Time. If you’d rather configure the API endpoints at build time, that works too. If you’re using Create React App, then you’ll have a global process.env available to get access to environment variables, including process.env.NODE_ENV, which will be set to “production” after a build.. Additionally, Create React App will only have access to environment REACT HOOK TO RUN CODE AFTER RENDER Can you run a hook before render? The short answer is no, not really.useEffect is the only hook that is meant for tying in to the component lifecycle, and it only ever runs after render. (useLayoutEffect is the same, it also runs after render).The longer answer is that technically, a React hook is just a function. And you could write a custom hook that’ll run before the component returns 4 EXAMPLES OF THE USESTATE HOOK useState returns an array with 2 elements, and we’re using ES6 destructuring to assign names to them. The first element is the current value of the state, and the second element is a state setter function – just call it with a new value, and the state will be set and the component will re-render. const =useState(true);
MODAL DIALOGS IN REACT When the App component first renders, its isOpen state is false, so the Modal is not rendered.. this. state = {isOpen: false};. Then when the user clicks the “Open the modal” button, it calls toggleModal which flips that flag to true.. toggleModal = => {this. setState ({isOpen:! this. state. isOpen});}. The setState call triggers a re-render, and now Modal gets passed show={true}, so it WAITING FOR PROMISES IN A LOOP Dave Ceddia’s Pure React is a work of enormous clarity and depth. Hats off. I'm a React trainer in London and would thoroughly recommend this to all front end devs wanting to upskill or consolidate. ACCESS-CONTROL-ALLOW-ORIGIN: DEALING WITH CORS ERRORS IN 2nd choice: Proxy Server. If you can’t modify the server, you can run your own proxy. And this proxy can return the Access-Control-Allow-Origin header if it’s not at the Same Origin as your page.. Instead of sending API requests to some remote server, you’ll make requests to your proxy, which will forward them to theremote server.
WORTHWHILE TESTING: WHAT TO TEST IN A REACT APP (AND WHY) Worthwhile Testing: What to test in a React app (and why) The promise of unit tests is grand: with proper tests in place, you can refactor code like crazy and have confidence that you didn’t break anything. You can add new features or tweak existing ones with that same level of confidence. When it comes time to actually write the tests though REDUX VS. THE REACT CONTEXT API React 16.3 added a new Context API – new in the sense that the old context API was a behind-the-scenes feature that most people either didn’t know about, or avoided using because the docs said to avoid using it. Now, though, the Context API is a first-class citizen in React, open to all (not that it wasn’t before, but it’s, like,official now).
DO I NEED NODE.JS IN THE BACKEND? I’ve seen a number of people asking this question, in a few different ways: My site is hosted on a PHP/MySQL backend and I read somewhere that I need to have a Node.js environment in the backend to use these new JavaScript libraries like React and Angular 2. REACT USECONTEXT HOOK TUTORIAL (WITH EXAMPLES) React Consumer example on CodeSandbox.. First, we create a new context, which we store in NumberContext.This is an object with 2 properties: Provider and Consumer.They’re a matched pair, and they’re born knowing how to communicate with each other (but not with other contexts). REACT STATE MANAGEMENT LIBRARIES AND HOW TO CHOOSE Here we’re passing an object containing the state and its setter, setState.Those two values are fine. setState will never change, and state only changes when you tell it to. The problem is the object wrapped around them, which will be created anew every time TheComponentWithState is rendered.. You might notice that the stuff we’re talking about here isn’t really about state management as REDUX SELECTORS: A QUICK TUTORIAL In our made-up example, it’s keeping track of the logged-in user, the products in your shop, and the items in the user’s shopping cart. The data here is normalized, so items in the shopping cart are referenced by ID.When a user adds an item to their cart, the item itself is not copied into the cart – only the item’s ID gets added to the shoppingCart.itemIds array. ACCESS THE REDUX STORE OUTSIDE A REACT COMPONENT The Redux FAQ has an entry on Can I import my store directly, and use it in components myself?.If you need the store in a React Component, there are better options, like using React-Redux and its connect function (more on that below!. Mark Erikson, one of the Redux maintainers, added a few thoughts on Reddit which I wanted to sharehere. He says:
HOW TO STRUCTURE YOUR REACT PROJECT HOW REDUX WORKS: A COUNTER-EXAMPLE Create a src/Counter.js with the code from the Counter example above.; On to the React Redux Example. As discussed in Part 1, Redux keeps the state of your app in a single store.Then, you can extract parts of that state and plug it into your components as props. This lets you keep data in one global place (the store) and feed it directly to any component in the app, without the gymnastics of 4 EXAMPLES OF THE USESTATE HOOK Once that’s done, the “read more” / “read less” links just need to call setHidden when they’re clicked.. useState returns an array with 2 elements, and we’re using ES6 destructuring to assign names to them. The first element is the current value of the state, and the second element is a state setter function – just call it with a new value, and the state will be set and the WHEN TO USELAYOUTEFFECT INSTEAD OF USEEFFECT (EXAMPLE) When to useLayoutEffect. The right time to useLayoutEffect instead? You’ll know it when you see it. Literally ;) If your component is flickering when state is updated – as in, it renders in a partially-ready state first and then immediately re-renders in its final state – that’s a good clue that it’s time to swap in useLayoutEffect.. This’ll be the case when your update is a 2-step USING REACT IN MULTIPLE ENVIRONMENTS Configure Endpoints at Build Time. If you’d rather configure the API endpoints at build time, that works too. If you’re using Create React App, then you’ll have a global process.env available to get access to environment variables, including process.env.NODE_ENV, which will be set to “production” after a build.. Additionally, Create React App will only have access to environment DO I NEED NODE.JS IN THE BACKEND? I’ve seen a number of people asking this question, in a few different ways: My site is hosted on a PHP/MySQL backend and I read somewhere that I need to have a Node.js environment in the backend to use these new JavaScript libraries like React and Angular 2. REACT USECONTEXT HOOK TUTORIAL (WITH EXAMPLES) React Consumer example on CodeSandbox.. First, we create a new context, which we store in NumberContext.This is an object with 2 properties: Provider and Consumer.They’re a matched pair, and they’re born knowing how to communicate with each other (but not with other contexts). REACT STATE MANAGEMENT LIBRARIES AND HOW TO CHOOSE Here we’re passing an object containing the state and its setter, setState.Those two values are fine. setState will never change, and state only changes when you tell it to. The problem is the object wrapped around them, which will be created anew every time TheComponentWithState is rendered.. You might notice that the stuff we’re talking about here isn’t really about state management as REDUX SELECTORS: A QUICK TUTORIAL In our made-up example, it’s keeping track of the logged-in user, the products in your shop, and the items in the user’s shopping cart. The data here is normalized, so items in the shopping cart are referenced by ID.When a user adds an item to their cart, the item itself is not copied into the cart – only the item’s ID gets added to the shoppingCart.itemIds array. ACCESS THE REDUX STORE OUTSIDE A REACT COMPONENT The Redux FAQ has an entry on Can I import my store directly, and use it in components myself?.If you need the store in a React Component, there are better options, like using React-Redux and its connect function (more on that below!. Mark Erikson, one of the Redux maintainers, added a few thoughts on Reddit which I wanted to sharehere. He says:
HOW TO STRUCTURE YOUR REACT PROJECT HOW REDUX WORKS: A COUNTER-EXAMPLE Create a src/Counter.js with the code from the Counter example above.; On to the React Redux Example. As discussed in Part 1, Redux keeps the state of your app in a single store.Then, you can extract parts of that state and plug it into your components as props. This lets you keep data in one global place (the store) and feed it directly to any component in the app, without the gymnastics of 4 EXAMPLES OF THE USESTATE HOOK Once that’s done, the “read more” / “read less” links just need to call setHidden when they’re clicked.. useState returns an array with 2 elements, and we’re using ES6 destructuring to assign names to them. The first element is the current value of the state, and the second element is a state setter function – just call it with a new value, and the state will be set and the WHEN TO USELAYOUTEFFECT INSTEAD OF USEEFFECT (EXAMPLE) When to useLayoutEffect. The right time to useLayoutEffect instead? You’ll know it when you see it. Literally ;) If your component is flickering when state is updated – as in, it renders in a partially-ready state first and then immediately re-renders in its final state – that’s a good clue that it’s time to swap in useLayoutEffect.. This’ll be the case when your update is a 2-step USING REACT IN MULTIPLE ENVIRONMENTS Configure Endpoints at Build Time. If you’d rather configure the API endpoints at build time, that works too. If you’re using Create React App, then you’ll have a global process.env available to get access to environment variables, including process.env.NODE_ENV, which will be set to “production” after a build.. Additionally, Create React App will only have access to environment DO I NEED NODE.JS IN THE BACKEND? I’ve seen a number of people asking this question, in a few different ways: My site is hosted on a PHP/MySQL backend and I read somewhere that I need to have a Node.js environment in the backend to use these new JavaScript libraries like React and Angular 2. HOW REDUX WORKS: A COUNTER-EXAMPLE Create a src/Counter.js with the code from the Counter example above.; On to the React Redux Example. As discussed in Part 1, Redux keeps the state of your app in a single store.Then, you can extract parts of that state and plug it into your components as props. This lets you keep data in one global place (the store) and feed it directly to any component in the app, without the gymnastics of USING REACT IN MULTIPLE ENVIRONMENTS Configure Endpoints at Build Time. If you’d rather configure the API endpoints at build time, that works too. If you’re using Create React App, then you’ll have a global process.env available to get access to environment variables, including process.env.NODE_ENV, which will be set to “production” after a build.. Additionally, Create React App will only have access to environment 4 EXAMPLES OF THE USESTATE HOOK Once that’s done, the “read more” / “read less” links just need to call setHidden when they’re clicked.. useState returns an array with 2 elements, and we’re using ES6 destructuring to assign names to them. The first element is the current value of the state, and the second element is a state setter function – just call it with a new value, and the state will be set and the RUN CODE IN REACT BEFORE RENDER Want to run some code before your React component renders? There are a few ways to make this work, and we’ll talk about them here. But, I have to warn you: Running code before render is usually a sign that you’re going against the grain of how React works.. TL;DR – There is no Before Render, only After REACT HOOK TO RUN CODE AFTER RENDER Can you run a hook before render? The short answer is no, not really.useEffect is the only hook that is meant for tying in to the component lifecycle, and it only ever runs after render. (useLayoutEffect is the same, it also runs after render).The longer answer is that technically, a React hook is just a function. And you could write a custom hook that’ll run before the component returns MODAL DIALOGS IN REACT When the App component first renders, its isOpen state is false, so the Modal is not rendered.. this. state = {isOpen: false};. Then when the user clicks the “Open the modal” button, it calls toggleModal which flips that flag to true.. toggleModal = => {this. setState ({isOpen:! this. state. isOpen});}. The setState call triggers a re-render, and now Modal gets passed show={true}, so it WAITING FOR PROMISES IN A LOOP Dave Ceddia’s Pure React is a work of enormous clarity and depth. Hats off. I'm a React trainer in London and would thoroughly recommend this to all front end devs wanting to upskill or consolidate. ACCESS-CONTROL-ALLOW-ORIGIN: DEALING WITH CORS ERRORS IN 2nd choice: Proxy Server. If you can’t modify the server, you can run your own proxy. And this proxy can return the Access-Control-Allow-Origin header if it’s not at the Same Origin as your page.. Instead of sending API requests to some remote server, you’ll make requests to your proxy, which will forward them to theremote server.
REDUX VS. THE REACT CONTEXT API React 16.3 added a new Context API – new in the sense that the old context API was a behind-the-scenes feature that most people either didn’t know about, or avoided using because the docs said to avoid using it. Now, though, the Context API is a first-class citizen in React, open to all (not that it wasn’t before, but it’s, like,official now).
DO I NEED NODE.JS IN THE BACKEND? I’ve seen a number of people asking this question, in a few different ways: My site is hosted on a PHP/MySQL backend and I read somewhere that I need to have a Node.js environment in the backend to use these new JavaScript libraries like React and Angular 2.DAVE CEDDIA
ARTICLES TO HELP YOU LEARN AND MASTER FRONTEND DEVELOPMENT WITH REACT.* Courses
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ARTICLES AND COURSES TO HELP YOU LEVEL UPLEVEL UP AS A FRONT ENDREACT DEVELOPER.
Learn React, withoutall the libraries.
Learn Redux & build an appstart-to-finish.
2020 Dave Ceddia.
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