animated-scroll

Allows animating scrollTop and/or scrollLeft of an HTML element. Uses requestAnimationFrame to provide smooth animations and returns a Promise to notify when the animation is completed. To ensure compatibility with older browsers, add polyfills for requestAnimationFrame and Promise as needed.

Installation

Install with bower:

bower install animated-scroll

Or with npm:

npm install animated-scroll

Or simply download the latest release.

Usage

The pre-built files can be found in the dist/ directory. dist/AnimatedScroll.min.js is minified and production-ready. It has a UMD wrapper so you can access it as:

var AnimatedScroll = require('dist/AnimatedScroll.min.js');
// or
import AnimatedScroll from 'dist/AnimatedScroll.min.js';
// or
define([ 'dist/AnimatedScroll.min.js' ], function (AnimatedScroll) {});
// or
var AnimatedScroll = window.AnimatedScroll;

Example

var element = document.getElementById('myElement');
var scroll = new AnimatedScroll(element);

scroll.top(100).then(function (newTop) {
    // newTop === 100
    console.log('#myElement\'s scrollTop is now', newTop);
});

scroll.left(100).then(function (newLeft) {
    // newLeft === 100
    console.log('#myElement\'s scrollLeft is now', newLeft);
});

scroll.to({
    left: 100,
    top: 100
}).then(function (coords) {
    console.log('#myElement\'s scrollTop is now', coords.top);
    console.log('#myElement\'s scrollLeft is now', coords.left);
});

API

AnimatedScroll.prototype.top(top [, duration [, easing]]) : Promise

Animates the scrollTop of element from it's current scrollTop to the new scrollTop in a time-frame of duration and using the provided easing function (duration and easing are optional).

It returns a promise which is resolved with the value of the new scrollTop when the animation is complete.

duration is in milliseconds and defaults to 400 if not provided. If set to 0 or false, then the scrollTop is set without animating. In this case an already fulfilled promise is returned.

If no easing is provided and duration is provided then the default easing function used is easeInOutQuad.

Calling .top on an element while a scrollTop animation is currently ongoing will stop that animation and start a new one i.e. animations are not queued. You can queue animations by hooking into the .then of the returned promise.

AnimatedScroll.prototype.left(top [, duration [, easing]]) : Promise

Exactly the same as .top but for scrollLeft :)

AnimatedScroll.prototype.to({ top, left } [, duration [, easing]]) : Promise

Convinient way to animate both scrollTop and scrollLeft. Accepts an object with top and left properties and returns a promise which resolves with an object containing the new top and left values.

AnimatedScroll.prototype.stopTop() : undefined

Stops any currently-running animation of scrollTop.

AnimatedScroll.prototype.stopLeft() : undefined

Stops any currently-running animation of scrollLeft.

AnimatedScroll.prototype.stop() : undefined

Stops any currently-running animation of scrollLeft or scrollTop.

Contributing

Contributions are welcomed! Here are the contribution guidelines.

First clone the repository and install dependencies:

npm install

To run tests:

npm test

To lint the code:

npm run lint

To make a production build:

npm run build

License

The MIT License