jd或者淘宝的具体商品有个放大镜的效果。虽然网上类似插件琳琅满目，应用到项目上有诸多不便，自己抽点时间自己写了个类似插件，积累下代码，何乐而不为呢!!let‘go:
打算把此特效封装成个插件，先把最基本的算法实现，然后再一步步封装吧：
最终实现效果：
html 代码：
复制代码 代码如下:
<div></div>
css 代码：
复制代码 代码如下:
<style>
* {
margin: 0;
padding: 0;
}
</style>
貌似什么都没有，开始咱们强大的js之旅吧：
javascript 代码：
复制代码 代码如下:
function createElement(MagnifierId, sImg, bImg) {
var Magnifier = $(MagnifierId);
Magnifier.style.position = 'relative';
//小图div
var smallDiv = $Create("div");
smallDiv.setAttribute("id", "small");
smallDiv.style.position = "absolute";
//遮罩层
var mask = $Create("div");
mask.setAttribute("id", "mask");
mask.style.position = "absolute";
//镜片
var mirror = $Create("div");
mirror.setAttribute("id", "mirror");
mirror.style.opacity = 0.3;
mirror.style.position = "absolute";
mirror.style.display = "none";
//小图
var smallImg = $Create("img");
smallImg.setAttribute("src", sImg);
smallImg.setAttribute("id", "smallImg");
smallImg.onload = function () {
//如果没设置放大镜的height或者width 根据小图大小设置放大镜大小
if (!Magnifier.offsetHeight) {
Magnifier.style.width = this.offsetWidth+"px";
Magnifier.style.height = this.offsetHeight + "px";
}
//遮罩层大小和小图一样
mask.style.opacity = "0";
mask.style.width = this.width + 'px';
mask.style.height = this.height + "px";
mask.style.zIndex = 2;
bigDiv.style.left = this.width + 5 + "px";
bigDiv.style.top = "-5px";
}
smallDiv.appendChild(mask);
smallDiv.appendChild(mirror);
smallDiv.appendChild(smallImg);
//视窗
var bigDiv = $Create("div");
bigDiv.setAttribute("id", "big");
bigDiv.style.position = "absolute";
bigDiv.style.overflow = "hidden";
bigDiv.style.display = "none";
var bigImg = $Create("img");
bigImg.setAttribute("src", bImg);
bigImg.setAttribute("id", "bigImg");
bigImg.style.position = "absolute";
bigDiv.appendChild(bigImg);
Magnifier.appendChild(smallDiv);
Magnifier.appendChild(bigDiv);
}
function setMagnifierStyle(mirrorStyle,shichuangStyle) {
//mirror
for (var item in mirrorStyle) {
mirror.style[item] = mirrorStyle[item];
}
for (var item in shichuangStyle) {
$("big").style[item] = shichuangStyle[item];
}
}
function registerEvent() {
$("mask").onmouseover = function () {
$("big").style.display = "block";
mirror.style.display = "block";
}
$("mask").onmouseout = function () {
$("big").style.display = "none";
mirror.style.display = "none";
}
$("mask").onmousemove = function (evt) {
var oEvent = evt || event;
var disX = oEvent.offsetX;
var disY = oEvent.offsetY;
var mirrorLeft = disX - mirror.offsetWidth / 2;
var mirrorTop = disY - mirror.offsetHeight / 2;
if (mirrorLeft < 0) {
mirrorLeft = 0;
}
else if (mirrorLeft > mask.offsetWidth - mirror.offsetWidth) {
mirrorLeft = mask.offsetWidth - mirror.offsetWidth;
}
if (mirrorTop < 0) {
mirrorTop = 0;
}
else if (mirrorTop > mask.offsetHeight - mirror.offsetHeight) {
mirrorTop = mask.offsetHeight - mirror.offsetHeight;
}
mirror.style.top = mirrorTop + "px";
mirror.style.left = mirrorLeft + "px";
var paX = mirrorTop / (mask.offsetHeight - mirror.offsetHeight);
var paY = mirrorLeft / (mask.offsetWidth - mirror.offsetWidth);
$("bigImg").style.top = -paX * ($("bigImg").offsetHeight - $("big").offsetHeight) + "px";
$("bigImg").style.left = -paY * ($("bigImg").offsetWidth - $("big").offsetWidth) + "px";
}
}
function $(id) {
return document.getElementById(id);
}
function $Create(type) {
return document.createElement(type);
}
最后再 onload小小的调用一下：
复制代码 代码如下: