react-on-screen

😎 Check if your react component are visible on the screen without pain and with performance in mind 😎!

• React on screen !npm() !npm() !license()

- [Demo](#demo)
- [Installation](#installation)
- [Usage](#usage)
    - [Simple](#simple)
    - [Using a render props](#using-a-render-props)
    - [Track the visibility only once](#track-the-visibility-only-once)
    - [Defining offset](#defining-offset)
    - [Partial visibility](#partial-visibility)
    - [Use the html tag of your choice](#use-the-html-tag-of-your-choice)
- [Api](#api)
- [Contributions](#contributions)
- [License](#license)

Demo

View the demo.

Installation

$ npm install --save react-on-screen
$ yarn add react-on-screen

A UMD build is also available :

<script src="./dist/ReactOnScreen.min.js"></script>

Usage

Simple

import React from 'react';
import TrackVisibility from 'react-on-screen';

const ComponentToTrack = ({ isVisible }) => {
    const style = {
        background: isVisible ? 'red' : 'blue'
    };
    return <div style={style}>Hello</div>;
}

const YourApp = () => {
    return (
       {/* Some Stuff */}
        <TrackVisibility>
            <ComponentToTrack />
        </TrackVisibility>
       {/* Some Stuff */}
    );
}

Using a render props

You can use a render props is you want to !

const YourApp = () => {
    return (
        <TrackVisibility>
            {({ isVisible }) => isVisible && <ComponentToTrack />}
        </TrackVisibility>
    );
}

Track the visibility only once

For many cases you may want to track the visibility only once. This can be done simply as follow :

const YourApp = () => {
    return (
        <TrackVisibility once>
            <ComponentToTrack />
        </TrackVisibility>
    );
}

Defining offset

Using offset props can be usefull if you want to lazy load an image for instance.

const YourApp = () => {
    return (
        <TrackVisibility offset={1000}>
            {({ isVisible }) => isVisible ? <ComponentToTrack /> : <Loading />}
        </TrackVisibility>
    );
}

Partial visibility

You may want to consider that a component is visible as soon as a part of the component is visible on screen. You can use the partialVisibility props for that.

const YourApp = () => {
    return (
        <TrackVisibility partialVisibility>
            {({ isVisible }) => <ComponentToTrack />}
        </TrackVisibility>
    );
}

Use the html tag of your choice

const YourApp = () => {
    return (
        <TrackVisibility partialVisibility tag="h1">
            {({ isVisible }) => <ComponentToTrack />}
        </TrackVisibility>
    );
}

Api

|props |type |default|description| |----------------|----------------|-------|-----------| |once |bool |false|If set to true track the visibility only once and remove the event listeners| |throttleInterval|int |150|Tweak the event listeners. See David Corbacho's article| |children |React Components| - |Can be one or many react components| |style |object | - |Style attributes| |className |string | - |Css classes| |offset |number | 0 |Allows you to specify how far left or above of the viewport you want to set isVisible to true| |partialVisibility|bool |false|Set isVisible to true on element as soon as any part is in the viewport| |tag |string|div |Allows specifying html tag of your choice|

Contributions

Any contributions is welcome !

• Develop: `` $ yarn start `
• Lint : ` $ yarn lint `
• Test : ` $ yarn test `
• Build : ` $ yarn build // will lint and run test before ``

License

Licensed under MIT