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listScroller.js
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listScroller.js
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/*
listScroller.js v 0.1.0
Author: Sudhanshu Yadav
Copyright (c) 2015 Sudhanshu Yadav - ignitersworld.com , released under the MIT license.
https://github.com/s-yadav/LongListScroller
*/
(function($,window) {
var nullFunc = function() {};
var defaults = {
scrollBodyClass: 'scroll-body',
listItemClass: 'list-item',
maxList: 50, //maximum list item on a page at a time
topLimit: 35, // top limit where element will be appended
bottomLimit: 15 // bottom limit where element will be prepended
};
//class for list scroll in web view
function ListScroller(container, options) {
this.container = $(container);
this.options = $.extend({}, defaults, options);
this.scrollBody = this.container.find('.' + this.options.scrollBodyClass);
}
ListScroller.prototype = {
constructor: ListScroller,
init: function() {
var self = this,
options = self.options,
maxList = options.maxList;
this.list = this.container.find('.' + this.options.listItemClass);
var currentRange = this.currentRange = {
from: 0,
to: 0
};
//get container height
function getContainerHeight() {
self.containerHeight = self.container.height();
}
getContainerHeight();
$(window).resize(getContainerHeight);
//calculate trigger points and set absolute positioning
var triggerPoints = this.triggerPoints = [];
var lastTop = 0;
var listTops = [];
this.list.each(function(index) {
var elm = $(this);
var top = lastTop;
listTops.push(lastTop);
lastTop += elm.outerHeight();
if (index % maxList == options.bottomLimit || index % maxList == options.topLimit) {
var lastTrigger = triggerPoints[triggerPoints.length - 1];
triggerPoints.push({
from: lastTrigger ? lastTrigger.to : 0,
fromIndx: lastTrigger ? lastTrigger.toIndx : 0,
toIndx: index,
to: lastTop
});
}
});
this.list.each(function(index) {
var elm = $(this);
elm.css({
position: 'absolute',
width: '100%',
top: listTops[index] + 'px',
});
});
this.list.detach();
//update height of scroll body
this.scrollBody.height(lastTop);
//remove scroll if its already create
if (this.iscroll) {
this.iscroll.destroy();
this.iscroll = null;
}
this.iscroll = new IScroll(this.container[0], {
lockDirection: true,
scrollbars: false,
tap: true,
mouseWheel: true,
probeType: 3,
deceleration: .0006
});
function filterElm(from, to, filterOn) {
return (filterOn || self.list).filter(function(idx) {
return idx >= from && idx < to;
});
}
function refreshView(from, to) {
from = Math.max(0, from);
to = Math.min(to, self.list.length);
var fromDiff = from - self.currentRange.from,
toDiff = to - self.currentRange.to;
var curList = self.scrollBody.find('.' + options.listItemClass);
if (fromDiff > 0) {
console.log('remove elm', filterElm(0, fromDiff, curList));
filterElm(0, fromDiff, curList).detach();
}
if (toDiff < 0) {
filterElm(curList.length + toDiff, curList.length, curList).detach();
}
if (fromDiff < 0) {
self.scrollBody.prepend(filterElm(from, self.currentRange.from));
}
if (toDiff > 0) {
self.scrollBody.append(filterElm(self.currentRange.to, to));
}
currentRange.from = from;
currentRange.to = to;
}
this.iscroll.on('scroll', function() {
var scrollTop = -self.iscroll.y + self.containerHeight / 2;
for (var i = 0, ln = triggerPoints.length; i < ln; i++) {
var obj = triggerPoints[i];
if (scrollTop >= obj.from && scrollTop < obj.to) {
if (i % 2) {
refreshView((i - 1) / 2 * maxList, (i + 1) / 2 * maxList);
} else {
refreshView((i - 2) / 2 * maxList, (i + 2) / 2 * maxList);
}
}
}
});
//to reset view port on initialization.
refreshView(0, maxList);
return this;
},
}
window.ListScroller = ListScroller;
}(jQuery,window,undefined));