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document.getElementById的简便方式

封装自己的元素获取方法,使元素获取变得简便

注意:1、应该要防止定义的被重写,可将同名的重新定义

     2、可将封装的对象置为全局对象,方便使用

 

通过id查找单个元素


 

封装方式:

//通过id查找单个元素(function (document){    //防止覆盖    var _overwrite = window._,        _;    _ = {        $ : function(id){            return typeof id === "string" ? document.getElementById(id) : id;        }    }    //将_置为全局对象    window._ = _;})(document);

 

 

测试:

<!DOCTYPE html><html><body>    <div id = "cloud">The cloud is beautiful</div></body><script><!--(function (document){    //防止覆盖    var _overwrite = window._,        _;    _ = {        $ : function(id){            return typeof id === "string" ? document.getElementById(id) : id;        }    }    //将_置为全局对象    window._ = _;})(document);var cloud = _.$("cloud");alert(cloud.innerHTML); //The cloud is beautiful--></script></html>

 

通过ID获取多个元素


 

封装方式:

//通过id查找一个或者多个元素(function (document){    //防止覆盖    var _overwrite = window._,        _;    _ = {        $ : function(/*ids....*/){            var elements = {},                    id,                    elt;            for(var i = 0, len= arguments.length; i < len; i++){                id = arguments[i];                elt = document.getElementById(id);                if(elt === null){                    throw new Error("No element with id:" + id);                }                if(len === 1){                    return elt;                }                elements[id] = elt;            }            return elements;                }    }    //将_置为全局对象    window._ = _;})(document);

 

测试:

 <div id = "cloud">The cloud is beautiful</div> <div id = "sea">The white white sea</div>//获取单个元素var cloud = _.$("cloud");alert(cloud.innerHTML);//The cloud is beautiful//获取多个元素var all = _.$("cloud", "sea");alert(all.cloud.innerHTML + "," + all.sea.innerHTML); //The cloud is beautiful,The white white sea