在一些数据展示的专题页里，有时候希望数字能动态从某一个数变化到另一个数，以此来吸引用户眼球，突出数据。

于是有了下文。

在这里，我用了两种方式：一种是原生的，另一种是jQuery插件。

数字线性变化的原理很简单，就是让数字增量变化，并循环动画。

原生JS版

首先获取DOM元素。为了兼容到IE6，兼容性方法如下：

var domUtil = { // 获取DOM元素 get: function(query) { var _this = this; if(document.querySelector) { return document.querySelector(query); } else { var elements = document; var queryStrArray = query.split(/ +/); for(var i = 0; i < queryStrArray.length; i++) { var domName = queryStrArray[i]; elements = _this.getElementsOfParentNode(domName, elements); } if(elements.length == 1) { return elements[0]; } else { return elements; } } }, // 获取DOM元素 getElementsOfParentNode: function(domName, parentNode) { var _this = this; parentNode = parentNode || document; domName = domName.trim(); var regExps = { id: /^#/, class: /^/ }; if(regExps.id.test(domName)) { domName = domName.replace(/^/#/g, ""); return parentNode.getElementById(domName); } else if(regExps.class.test(domName)) { domName = domName.replace(/^./g, ""); return _this.getElementsByClassName(domName, parentNode); } else { return parentNode.getElementsByTagName(domName); } }, // 获取class元素的兼容方法 getElementsByClassName: function(className, parentNode) { if(parentNode.getElementsByClassName){ return parentNode.getElementsByClassName(className); } else { className = className.replace(/^ +| +$/g,""); var classArray = className.split(/ +/); var eles = parentNode.getElementsByTagName("*"); for(var i = 0;i < classArray.length; i++){ var classEles = []; var reg = new RegExp("(^| )" + classArray[i] + "( |$)"); for(var j = 0;j < eles.length; j++){ var ele = eles[j]; if(reg.test(ele.className)){ classEles.push(ele); } } eles = classEles; } return eles; } } }; /* * 数字动画（目前仅支持数字动画的线性变化） * options参数： * element {String} DOM元素query字符串 * from {Number} 起始数字 * to {Number} 终点数字 * duration {Number} 动画时间 * callback {Function} 数字变化时的回调函数 */ var animatingNumber = function(options) { this.element = domUtil.get(options.element); this.startNum = options.from; this.endNum = options.to; this.duration = options.duration || 2000; this.callback = options.callback; this.timer = null; }; animatingNumber.prototype = { start: function() { var _this = this; _this.animate(); }, stop: function() { if(this.timer) { clearTimeout(this.timer); this.timer = null; } }, animate: function() { var _this = this; var curNum = _this.startNum; var animateTime = 0; var range = _this.endNum - _this.startNum; var timerStep = Math.abs( Math.floor(_this.duration / range) ); timerStep = timerStep > 20 ? timerStep : 20; var numStep = (range / _this.duration) * timerStep; _this.stop(); (function animate() { _this.timer = setTimeout(function() { curNum = Math.ceil( curNum + numStep ); if( (_this.endNum > _this.startNum && curNum >= _this.endNum) || (_this.endNum < _this.startNum && curNum <= _this.endNum) ) { curNum = _this.endNum; } _this.element.innerText = curNum; animateTime++; if(typeof this.callback == 'function') { this.callback(curNum); } animate(); if(curNum >= _this.endNum) { _this.stop(); } }, timerStep); })(); } }; animatingNumber.create = function(options) { return new animatingNumber(options); };

使用：

<p>Number: <span>500</span></p> <script> animatingNumber.create({ element: '.dynamicNum', from: 1, to: 500, duration: 2000 }).start(); </script>

效果如下：

jQuery插件版

原理同上，只是DOM元素获取使用jQuery方法，并把数字动画方法封装成jQuery插件。如下：

/* * 数字动画（目前仅支持数字动画的线性变化） * options参数： * from {Number} 起始数字 * to {Number} 终点数字 * duration {Number} 动画时间 * callback {Function} 数字变化时的回调函数 */ (function( $ ) { $.fn.animatingNumber = function(options) { var settings = { element: this, startNum: options.from, endNum: options.to, duration: options.duration || 2000, callback: options.callback }; var timer = null; var methods = { start: function() { var _this = this; _this.animate(); }, stop: function() { if(timer) { clearTimeout(timer); timer = null; } }, animate: function() { var _this = this; var curNum = settings.startNum; var animateTime = 0; var range = settings.endNum - settings.startNum; var timerStep = Math.abs( Math.floor(settings.duration / range) ); timerStep = timerStep > 20 ? timerStep : 20; var numStep = (range / settings.duration) * timerStep; _this.stop(); (function animate() { timer = setTimeout(function() { curNum = Math.ceil( curNum + numStep ); if( (settings.endNum > settings.startNum && curNum >= settings.endNum) || (settings.endNum < settings.startNum && curNum <= settings.endNum) ) { curNum = settings.endNum; } settings.element.text(curNum); animateTime++; if(typeof settings.callback == 'function') { settings.callback(curNum); } animate(); if(curNum >= settings.endNum) { _this.stop(); } }, timerStep); })(); } }; return this.each(function() { return methods.start(); }); }; })( jQuery );

使用：

<p>Number: <span></span></p> <script> $('.dynamicNum').animatingNumber({ from: 1, to: 1000, duration: 2000 }); </script>

效果如下：