Zachary Palmer

Zachary Palmer

1562836889

Build an Infinite Scroll in React using React Hooks

The infinite list (scroll) feature has existed for a while. It’s a great way to enhance your application’s UX.

There are many third-party libraries available, but if you like to challenge yourself as I do, we’ll explore the implementation from scratch using Hooks in this post.

Let’s quick code a simple app component. We initialize an empty state and pass references to the state and setState as props to our InfiniteList component.

export default function App() {
  
  const [state, setState] = useState([]);
return (
    <div className='App'>
      <InfiniteList 
        state={state}
        setState={setState}
      />
    </div>
  );
};

The InfiniteList component will return an unordered list of dog images fetched from the Dog API.

Once our request is successful, we push the images to the parent’s state. We’ll make sure not to overwrite the previous state, as we’ll use the getData() function multiple times to fetch more images. So, dot dot dot . . .

function InfiniteList(props) {
useEffect(() => {
    getData();
  }, []);
const getData = () => {
    fetch('https://dog.ceo/api/breeds/image/random/15')
      .then(res => {
        return !res.ok 
        ? res.json().then(e => Promise.reject(e))
        : return res.json()
      }
      .then(res => props.setState([...props.state, ...res.message]))
      .catch(console.log);
}
return (
    <ul id='list'>
      { props.state.map((img, i) => (
          <li key={i} style={{backgroundImage: `url(${img})`}}/>)}
    </ul>
  );

So far, this displays the first 15 images.

Now we need to listen for an event when a user scrolls down to the very bottom of the viewport, and fetches more images, calling getData() again.

But how do we determine the bottom reach? I hope this image will help you to understand.

  1. window.innerHeight<strong> </strong>— static, the height of the user’s browser window.
  2. window.scrollY — dynamic property, current scroll position.
  3. list.clientHeight — static, the height of the container (ul element).
  4. list.offsetTop — container’s indent (if any) from the top of the page, static.

Okay, if 1+2===3+4, we know that a user is at the bottom of the page and we need to fetch.

But what if we want the ul to be a fixed height? We need to get the ul’s properties:

  1. element.scrollHeight — static value, the total scrollable height.
  2. element.scrollTop** **— dynamic value, the current scroll top position.
  3. element.clientHeight — static value, element’s current height (excluding overflow).

Hence, 1===2+3 will indicate that the user has reached the bottom of the container. And now we can conditionally tell the component whether it’s of fixed height, by setting the scrollable property.

Let’s put this all together in the new useEffect hook.

There’s one last fix to make this all work. Let’s initialize a state, then, once the condition above is met, we toggle the state, giving it a signal to fetch more, by making our first hook dependent on the state’s value.

const [loadMore, setLoadMore] = useState(false);useEffect(() => {
  setLoadMore(false);
  getData();
}, [loadMore]);

We can also conditionally render a loading spinner at the bottom while waiting for the API response, by initializing a new state with some truthy value, and then resetting it once the request is fulfilled.

Also, to avoid potential bugs, we could remove the event listener from the window object when the component unmounts, by adding a return statement in useEffect like so:

useEffect(() => {
  widnow.addEventListener('event', function);
  return () => {
    window.removeEventListener('event', function);
  }
}, [])

#reactjs #web-development

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Build an Infinite Scroll in React using React Hooks
Autumn  Blick

Autumn Blick

1598839687

How native is React Native? | React Native vs Native App Development

If you are undertaking a mobile app development for your start-up or enterprise, you are likely wondering whether to use React Native. As a popular development framework, React Native helps you to develop near-native mobile apps. However, you are probably also wondering how close you can get to a native app by using React Native. How native is React Native?

In the article, we discuss the similarities between native mobile development and development using React Native. We also touch upon where they differ and how to bridge the gaps. Read on.

A brief introduction to React Native

Let’s briefly set the context first. We will briefly touch upon what React Native is and how it differs from earlier hybrid frameworks.

React Native is a popular JavaScript framework that Facebook has created. You can use this open-source framework to code natively rendering Android and iOS mobile apps. You can use it to develop web apps too.

Facebook has developed React Native based on React, its JavaScript library. The first release of React Native came in March 2015. At the time of writing this article, the latest stable release of React Native is 0.62.0, and it was released in March 2020.

Although relatively new, React Native has acquired a high degree of popularity. The “Stack Overflow Developer Survey 2019” report identifies it as the 8th most loved framework. Facebook, Walmart, and Bloomberg are some of the top companies that use React Native.

The popularity of React Native comes from its advantages. Some of its advantages are as follows:

  • Performance: It delivers optimal performance.
  • Cross-platform development: You can develop both Android and iOS apps with it. The reuse of code expedites development and reduces costs.
  • UI design: React Native enables you to design simple and responsive UI for your mobile app.
  • 3rd party plugins: This framework supports 3rd party plugins.
  • Developer community: A vibrant community of developers support React Native.

Why React Native is fundamentally different from earlier hybrid frameworks

Are you wondering whether React Native is just another of those hybrid frameworks like Ionic or Cordova? It’s not! React Native is fundamentally different from these earlier hybrid frameworks.

React Native is very close to native. Consider the following aspects as described on the React Native website:

  • Access to many native platforms features: The primitives of React Native render to native platform UI. This means that your React Native app will use many native platform APIs as native apps would do.
  • Near-native user experience: React Native provides several native components, and these are platform agnostic.
  • The ease of accessing native APIs: React Native uses a declarative UI paradigm. This enables React Native to interact easily with native platform APIs since React Native wraps existing native code.

Due to these factors, React Native offers many more advantages compared to those earlier hybrid frameworks. We now review them.

#android app #frontend #ios app #mobile app development #benefits of react native #is react native good for mobile app development #native vs #pros and cons of react native #react mobile development #react native development #react native experience #react native framework #react native ios vs android #react native pros and cons #react native vs android #react native vs native #react native vs native performance #react vs native #why react native #why use react native

What are hooks in React JS? - INFO AT ONE

In this article, you will learn what are hooks in React JS? and when to use react hooks? React JS is developed by Facebook in the year 2013. There are many students and the new developers who have confusion between react and hooks in react. Well, it is not different, react is a programming language and hooks is a function which is used in react programming language.
Read More:- https://infoatone.com/what-are-hooks-in-react-js/

#react #hooks in react #react hooks example #react js projects for beginners #what are hooks in react js? #when to use react hooks

Erna  Herzog

Erna Herzog

1626748440

Build a React Accordion from Scratch Using React Hooks and No Extra Dependencies

Follow these step-by-step instructions to create an animated accordion component in React.js using React Hooks and CSS.

🗂 DOWNLOADS 🗂

https://gum.co/AEeem

🔗 HELPFUL RESOURCES 🔗

React DOM Elements: https://reactjs.org/docs/dom-elements.html

Overview of dangerouslySetInnerHTML: https://react-cn.github.io/react/tips/dangerously-set-inner-html.html

How to prevent XSS attacks when using dangerouslySetInnerHTML in React: https://dev.to/jam3/how-to-prevent-xss-attacks-when-using-dangerouslysetinnerhtml-in-react-1464

Hooks API Reference: https://reactjs.org/docs/hooks-reference.html

Visual Studio Code: https://code.visualstudio.com/

#react #react hooks #react accordion #css #react.js

React Tutorial: How To Build a Virtualized List with Infinite Scroll and a Hook

When rendering a large set of data (e.g. list, table, etc.) in React, we all face performance/memory troubles. However, we can use the technique of  DOM recycling to solve the troubles.

Fortunately, there’re  some great libraries already available but most of them are component-based solutions and it’s not possible to implement the feature of infinite scroll (or lazily loading) through a single component. So the bundle size might be a concern.

Today, I want to show you how to build a virtualized list with infinite scroll by just using a hook. You might think: hmm… could it be possible? Yep! no kidding. Let’s take a look.

#react #hooks #performance #infinite-scrolling #typescript

Hayden Slater

1599277908

Validating React Forms With React-Hook-Form

Validating inputs is very often required. For example, when you want to make sure two passwords inputs are the same, an email input should in fact be an email or that the input is not too long. This is can be easily done using React Hook From. In this article, I will show you how.

Required Fields

The most simple, yet very common, validation is to make sure that an input component contains input from the user. React Hook Form basic concept is to register input tags to the form by passing register() to the tag’s ref attribute. As we can see here:

#react-native #react #react-hook-form #react-hook