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README.md

sweet-scroll

Build Status npm version David License

ECMAScript2015+ & TypeScript Friendly, dependency-free smooth scroll library.

🍭 See Demo

Features

  • Dependecy-free!!
  • ECMAScript2015+ & TypeScript friendly
  • Use requestAnimationFrame API
  • Supports vertical and horizontal scroll
  • Supports dynamic trigger (event delegation)
  • Supports container for the scroll
  • Supports many easing types
  • Supports server-side rendering (Can load without putting out errors.)

Table of Contents

Usage

1. Install

via NPM

$ npm install sweet-scroll
use
import SweetScroll from 'sweet-scroll';

via MANUAL

  1. Download the sweet-scroll.min.js
  2. Load it in the script tag.
<script src="sweet-scroll.min.js"></script>

via CDN (UNPKG)

<script src="https://unpkg.com/sweet-scroll/sweet-scroll.min.js"></script>

2. Setup of HTML

<a href="#intro" data-scroll>Go to Introduction</a>
...
<div id="intro">Introduction</div>

3. Initialize SweetScroll

You need to initialize an instance after DOMContentLoaded.

document.addEventListener('DOMContentLoaded', () => {
  const scroller = new SweetScroll({/* some options */});
}, false);

Options

The following options are applied by default. It can be customized as needed.

{
  trigger: '[data-scroll]',       // Selector for trigger (must be a valid css selector)
  header: '[data-scroll-header]', // Selector or Element for fixed header (Selector of must be a valid css selector)
  duration: 1000,                 // Specifies animation duration in integer
  easing: 'easeOutQuint',         // Specifies the pattern of easing
  offset: 0,                      // Specifies the value to offset the scroll position in pixels
  vertical: true,                 // Enable the vertical scroll
  horizontal: false,              // Enable the horizontal scroll
  cancellable: true,              // When fired wheel or touchstart events to stop scrolling
  updateURL: false,               // Update the URL hash on after scroll (true | false | 'push' | 'replace')
  preventDefault: true,           // Cancels the container element click event
  stopPropagation: true,          // Prevents further propagation of the container element click event in the bubbling phase
  quickMode: false,               // Instantly scroll to the destination! (It's recommended to use it with `easeOutExpo`)

  // Callbacks
  before: null,
  after: null,
  cancel: null,
  complete: null,
  step: null,
}

Easings

Supports the following easing.

Built-in (22)

  • Normal
    • linear
  • Quad
    • easeInQuad
    • easeOutQuad
    • easeInOutQuad
  • Cubic
    • easeInCubic
    • easeOutCubic
    • easeInOutCubic
  • Quart
    • easeInQuart
    • easeOutQuart
    • easeInOutQuart
  • Quint
    • easeInQuint
    • easeOutQuint (default)
    • easeInOutQuint
  • Sine
    • easeInSine
    • easeOutSine
    • easeInOutSine
  • Expo
    • easeInExpo
    • easeOutExpo
    • easeInOutExpo
  • Circ
    • easeInCirc
    • easeOutCirc
    • easeInOutCirc

Advanced (9)

Easing functions that are not built in can pass functions directly.

const scroller = new SweetScroll({
  easing: advancedEasingFunction,
});

Elastic

easeInElastic
const easeInElastic = (_, t, b, c, d) => {
  let s = 1.70158;
  let p = 0;
  let a = c;
  if (t === 0) return b;
  if ((t /= d) === 1) return b + c;
  if (!p) p = d * 0.3;
  if (a < Math.abs(c)) {
    a = c;
    s = p / 4;
  } else {
    s = p / (2 * Math.PI) * asin(c / a);
  }
  return -(a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;
};
easeOutElastic
const easeOutElastic = (_, t, b, c, d) => {
  let s = 1.70158;
  let p = 0;
  let a = c;
  if (t === 0) return b;
  if ((t /= d) === 1) return b + c;
  if (!p) p = d * 0.3;
  if (a < Math.abs(c)) {
    a = c;
    s = p / 4;
  } else {
    s = p / (2 * Math.PI) * asin(c / a);
  }
  return a * Math.pow(2, -10 * t) * Math.sin((t * d - s) * (2 * Math.PI) / p) + c + b;
};
easeInOutElastic
const easeInOutElastic = (_, t, b, c, d) => {
  let s = 1.70158;
  let p = 0;
  let a = c;
  if (t === 0) return b;
  if ((t /= d / 2) === 2) return b + c;
  if (!p) p = d * (0.3 * 1.5);
  if (a < Math.abs(c)) {
    a = c;
    s = p / 4;
  } else {
    s = p / (2 * Math.PI) * Math.asin(c / a);
  }
  if (t < 1) {
    return -0.5 * (a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;
  }
  return a * Math.pow(2, -10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p) * 0.5 + c + b;
};

Back

easeInBack
const easeInBack = (_, t, b, c, d, s = 1.70158) => (
  c * (t /= d) * t * ((s + 1) * t - s) + b
);
easeOutBack
const easeOutBack = (_, t, b, c, d, s = 1.70158) => (
  c * ((t = t / d - 1) * t * ((s + 1) * t + s) + 1) + b
);
easeInOutBack
const easeInOutBack = (_, t, b, c, d, s = 1.70158) => (
  (t /= d / 2) < 1
    ? c / 2 * (t * t * (((s *= (1.525)) + 1) * t - s)) + b
    : c / 2 * ((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2) + b
);

Bounce

easeOutBounce
const easeOutBounce = (_, t, b, c, d) => {
  if ((t /= d) < (1 / 2.75)) {
    return c * (7.5625 * t * t) + b;
  } else if (t < (2 / 2.75)) {
    return c * (7.5625 * (t -= (1.5 / 2.75)) * t + 0.75) + b;
  } else if (t < (2.5 / 2.75)) {
    return c * (7.5625 * (t -= (2.25 / 2.75)) * t + 0.9375) + b;
  }
  return c * (7.5625 * (t -= (2.625 / 2.75)) * t + 0.984375) + b;
};
easeInBounce
const easeOutBounce = (_, t, b, c, d) => {
  if ((t /= d) < (1 / 2.75)) {
    return c * (7.5625 * t * t) + b;
  } else if (t < (2 / 2.75)) {
    return c * (7.5625 * (t -= (1.5 / 2.75)) * t + 0.75) + b;
  } else if (t < (2.5 / 2.75)) {
    return c * (7.5625 * (t -= (2.25 / 2.75)) * t + 0.9375) + b;
  }
  return c * (7.5625 * (t -= (2.625 / 2.75)) * t + 0.984375) + b;
};

const easeInBounce = (x, t, b, c, d) => (
  c - easeOutBounce(x, d - t, 0, c, d) + b
);
easeInOutBounce
const easeOutBounce = (_, t, b, c, d) => {
  if ((t /= d) < (1 / 2.75)) {
    return c * (7.5625 * t * t) + b;
  } else if (t < (2 / 2.75)) {
    return c * (7.5625 * (t -= (1.5 / 2.75)) * t + 0.75) + b;
  } else if (t < (2.5 / 2.75)) {
    return c * (7.5625 * (t -= (2.25 / 2.75)) * t + 0.9375) + b;
  }
  return c * (7.5625 * (t -= (2.625 / 2.75)) * t + 0.984375) + b;
};

const easeInBounce = (x, t, b, c, d) => (
  c - easeOutBounce(x, d - t, 0, c, d) + b
);

const easeInOutBounce = (x, t, b, c, d) => (
  t < d / 2
    ? easeInBounce(x, t * 2, 0, c, d) * 0.5 + b
    : easeOutBounce(x, t * 2 - d, 0, c, d) * 0.5 + c * 0.5 + b
);

Live demo

Customizing Tips

Specifying container elements

In the following example we have specified in the container for scrolling the #container.

<div id="container">
  <a href="#heading2" data-scroll>Go to Heading2</a>
  ...
  <h2 id="heading2">Heading2</h2>
</div>
// Specified in the CSS Selector
const scroller = new SweetScroll({/* some options */}, '#container');

// Specified in the Element
const scroller = new SweetScroll({/* some options */}, document.getElementById('container'));

Specify fixed header

Add the data-scroll-header attribute in order to offset the height of the fixed header.

<header data-scroll-header></header>

Specify the CSS Selector in header option instead of the data-scroll-header attribute.

const scroller = new SweetScroll({
  header: '#header',
});

Override of options for each element

You can override the default options by passing the option in JSON format to the data-scroll-options.

<a href="#target" data-scroll data-scroll-options='{"easing": "easeOutExpo"}'>Go to Target</a>

if you want to use in non anchor element

Will use the data-scroll attribute instead of href.

<button type="button" data-scroll="+=500">Scroll under 500px</button>

Do you feel scrolling is slow?

You can solve with quickMode options!

const scroller = new SweetScroll({
  quickMode: true,
  easing: 'easeOutExpo', // Recommended
});

quickMode finishes scrolling in a moment.

Scrolling animation in another page

The following, Introduce one of the mounting method.

document.addEventListener('DOMContentLoaded', () => {
  const scroller = new SweetScroll();
  const hash = window.location.hash;
  const needsInitialScroll = document.getElementById(hash.substr(1)) != null;

  if (needsInitialScroll) {
    window.location.hash = '';
  }

  window.addEventListener('load', () => {
    if (needsInitialScroll) {
      scroller.to(hash, { updateURL: 'replace' });
    }
  }, false);
}, false);

Live demo

You can also achieve the same thing in other ways by using the provided API.

API

new SweetScroll(options?: PartialOptions, container?: string | Element)

Will generate a SweetScroll instance.

Example:

const scroller = new SweetScroll({
  duration: 1200,
  easing: 'easeOutExpo',
}, '#container');

SweetScroll.create(options?: PartialOptions, container?: string | Element)

Will generate a SweetScroll instance. (factory method)

Example:

const scroller = SweetScroll.create({
  duration: 1200,
  easing: 'easeOutExpo',
}, '#container');

to(distance: any, options?: PartialOptions)

Scroll animation to the specified distance.
distance to can specify the CSS Selector or scroll position.

Example:

const scroller = new SweetScroll();

// CSS Selector of target element
scroller.to('#footer');

// Object
scroller.to({ top: 1000, left: 20 });

// Array (top:0, left:1000)
scroller.to([0, 1000]);

// Number (Priority to vertical scroll position. by default.)
scroller.to(500);

// String (Relative position)
scroller.to('+=500');
scroller.to('-=200');

toTop(distance: any, options?: PartialOptions)

Vertical scroll animation to the specified distance.

Example:

scroller.toTop(0);

toLeft(distance: any, options?: PartialOptions)

Horizontal scroll animation to the specified distance.

Example:

scroller.toLeft(1500);

toElement($el: Element, options?: PartialOptions)

Scroll animation to the specified Element.

Example:

scroller.toElement(document.getElementById('content'));

update(options: PartialOptions)

Will update the SweetScroll instance.
Primarily used in the case of option update.

Example:

scroller.update({
  trigger: 'a[href^="#"]',
  duration: 3000,
});

stop(gotoEnd: boolean = true)

gotoEnd: {Boolean}

Will stop the current scroll animation.

Example:

scroller.stop(true);

destroy()

Will destroy the SweetScroll instance.
Disable of the method and event handler.

Example:

scroller.destroy();

Callbacks

In before and after, you will pass the coordinates and the triggering element in the argument.
In addition, you can stop the scrolling by return a before in false.

Example:

const scroller = new SweetScroll({

  // Stop scrolling case of trigger element that contains the `is-disabled` class.
  before: (offset: Offset, $trigger: Element | null, scroller: SweetScroll): boolean | void => {
    console.log('Before!!', offset, scroller);
    if ($trigger && $trigger.classList.contains('is-disabled')) {
      return false;
    }
  },

  // If the `wheel` or `touchstart` event is called
  cancel: (scroller: SweetScroll): void => {
    console.log('Cancel!!', scroller);
  },

  // Scroll animation is complete
  after: (offset: Offset, $trigger: Element | null, scroller: SweetScroll): void => {
    console.log('After!!', offset, $trigger, scroller);
  },

  // Scroll animation is complete (`after` or `cancel`)
  complete: (isCancel: boolean, scroller: SweetScroll): void => {
    console.log('Complete!!', isCancel, scroller);
  },

  // Each animation frame
  step: (time: number, scroller: SweetScroll): void => {
    console.log('step', time, scroller);
  },
});

Extends Class:

The following is a pattern to override a method in the inheritance destination class.

import SweetScroll, { Offset } from 'sweet-scroll';

class MyScroll extends SweetScroll {
  protected onBefore(offset: Offset, $trigger: Element | null): boolean | void {
    // Stop scrolling case of trigger element that contains the `is-disabled` class.
    console.log('Before!!', offset);
    if ($trigger && $trigger.classList.contains('is-disabled')) {
      return false;
    }
  }

  protected onCancel(): void {
    console.log('Canell!!');
  }

  protected onAfter(offset: Offset, $trigger: Element | null): void {
    console.log('After!!', offset, $trigger);
  }

  protected onComplete(isCancel: boolean): void {
    console.log('Complete!!', isCancel);
  }

  protected onStep(time: number): void {
    console.log('step', time);
  }
}

Browser Support

Works in IE10+, and all modern browsers.

Scrolling with IE9

It is necessary to use polyfill or ponyfill of requestAnimationFrame.

Example ponyfill

Using raf module.

import raf from 'raf';
import SweetScroll from 'sweet-scroll';

SweetScroll.raf = raf;
SweetScroll.caf = raf.cancel;

CHANGELOG

See the CHANGELOG.md

Contibute

  1. Fork it!
  2. Create your feature branch: git checkout -b my-new-feature
  3. Commit your changes: git commit -am 'Add some feature'
  4. Push to the branch: git push origin my-new-feature
  5. Submit a pull request 💪

Bugs, feature requests and comments are more than welcome in the issues.

Development

We will develop using the following npm scripts.

npm start

Launch the local server and let the demo run. Opening http://localhost:3000 in your browser.

npm run build

Compile TypeScript and create type definitions.

npm run test

Run unit testing with Jest.

License

MIT © tsuyoshiwada