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Detailed introduction to Javascript encapsulation id, class and element selector sample code sharing

黄舟
Release: 2017-03-20 15:01:45
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这篇文章主要给大家介绍了Javascript封装id、class与元素选择器的方法,文中给出了详细的示例代码,对大家的理解和学习具有一定的参考价值,需要的朋友们下面来一起看看吧。

由于各个浏览器都支持的选择方法只有如下三种:

     1、document.getElementById()

     2、document.getElementsByName()

     3、document.getElementsByTagName()

所以在封装选择器的时候要考虑浏览器的兼容性。

示例代码如下:

<script>//封装id选择器
  function $(selector){
    var c=selector.substring(0,1);//获取第一个字符
    if(c=="#"){
      return document.getElementById(selector.substring(1,selector.length));//返回相应的元素
    }
  }
  
  
  //封装class选择器
  function $(selector){
    var className=selector.substring(1);//从索引为1的元素往后取
    //判断浏览器是否支持getElementsByClassName
    if(document.getElementsByClassName){
      return document.getElementsByClassName(className)
      //document.querySelectorAll(&#39;.cls&#39;)兼容性有问题
    }else{
      //document.getElementsByTagName(&#39;*&#39;)+正则表达式
      //\s空白字符 ^开始 $结束
      var reg=new RegExp(&#39;^|\\s&#39;+className+&#39;$|\\s&#39;);
      var elems=document.getElementsByTagName("*");//获取页面中所有元素
      var arr=[];//保存获取到的指定className的元素
      for(var i=0;i<elems.length;i++){
        if(reg.test(elems[i].className)){//如果和模式匹配上
          arr.push(elem[i]);
        }
      }
      return arr;
    }
  }
  
  //封装标签选择器  
  function $(element){
    return document.getElementsByTagName(element);
  }
 </script>
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