131 lines
3.9 KiB
JavaScript
131 lines
3.9 KiB
JavaScript
/*! iNoBounce - v0.1.6
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* https://github.com/lazd/iNoBounce/
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* Copyright (c) 2013 Larry Davis <lazdnet@gmail.com>; Licensed BSD */
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(function(global) {
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// Stores the Y position where the touch started
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var startY = 0;
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// Store enabled status
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var enabled = false;
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var supportsPassiveOption = false;
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try {
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var opts = Object.defineProperty({}, 'passive', {
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get: function() {
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supportsPassiveOption = true;
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}
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});
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window.addEventListener('test', null, opts);
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} catch (e) {}
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var handleTouchmove = function(evt) {
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// Get the element that was scrolled upon
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var el = evt.target;
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// Check all parent elements for scrollability
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while (el !== document.body && el !== document) {
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// Get some style properties
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var style = window.getComputedStyle(el);
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if (!style) {
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// If we've encountered an element we can't compute the style for, get out
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break;
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}
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// Ignore range input element
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if (el.nodeName === 'INPUT' && el.getAttribute('type') === 'range') {
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return;
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}
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var scrolling = style.getPropertyValue('-webkit-overflow-scrolling');
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var overflowY = style.getPropertyValue('overflow-y');
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var height = parseInt(style.getPropertyValue('height'), 10);
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// Determine if the element should scroll
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var isScrollable = scrolling === 'touch' && (overflowY === 'auto' || overflowY === 'scroll');
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var canScroll = el.scrollHeight > el.offsetHeight;
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if (isScrollable && canScroll) {
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// Get the current Y position of the touch
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var curY = evt.touches ? evt.touches[0].screenY : evt.screenY;
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// Determine if the user is trying to scroll past the top or bottom
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// In this case, the window will bounce, so we have to prevent scrolling completely
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var isAtTop = (startY <= curY && el.scrollTop === 0);
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var isAtBottom = (startY >= curY && el.scrollHeight - el.scrollTop === height);
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// Stop a bounce bug when at the bottom or top of the scrollable element
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if (isAtTop || isAtBottom) {
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evt.preventDefault();
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}
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// No need to continue up the DOM, we've done our job
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return;
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}
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// Test the next parent
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el = el.parentNode;
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}
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// Stop the bouncing -- no parents are scrollable
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evt.preventDefault();
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};
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var handleTouchstart = function(evt) {
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// Store the first Y position of the touch
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startY = evt.touches ? evt.touches[0].screenY : evt.screenY;
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};
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var enable = function() {
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// Listen to a couple key touch events
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window.addEventListener('touchstart', handleTouchstart, supportsPassiveOption ? { passive : false } : false);
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window.addEventListener('touchmove', handleTouchmove, supportsPassiveOption ? { passive : false } : false);
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enabled = true;
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};
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var disable = function() {
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// Stop listening
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window.removeEventListener('touchstart', handleTouchstart, false);
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window.removeEventListener('touchmove', handleTouchmove, false);
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enabled = false;
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};
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var isEnabled = function() {
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return enabled;
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};
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// Enable by default if the browser supports -webkit-overflow-scrolling
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// Test this by setting the property with JavaScript on an element that exists in the DOM
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// Then, see if the property is reflected in the computed style
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var testDiv = document.createElement('div');
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document.documentElement.appendChild(testDiv);
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testDiv.style.WebkitOverflowScrolling = 'touch';
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var scrollSupport = 'getComputedStyle' in window && window.getComputedStyle(testDiv)['-webkit-overflow-scrolling'] === 'touch';
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document.documentElement.removeChild(testDiv);
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if (scrollSupport) {
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enable();
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}
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// A module to support enabling/disabling iNoBounce
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var iNoBounce = {
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enable: enable,
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disable: disable,
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isEnabled: isEnabled
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};
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if (typeof module !== 'undefined' && module.exports) {
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// Node.js Support
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module.exports = iNoBounce;
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}
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if (typeof global.define === 'function') {
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// AMD Support
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(function(define) {
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define('iNoBounce', [], function() { return iNoBounce; });
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}(global.define));
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}
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else {
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// Browser support
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global.iNoBounce = iNoBounce;
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}
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}(this));
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