js 为数组编写该方法;indexOf 

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script>
    /*var str = 'aaaaaaaasddfggdkfhndfre';
    *indexOf('s')为数组编写该方法;indexOf('img/1.jpg');
    */
    window.onload = function(){
        var arrImg = ['img/1.jpg','img/2.jpg','img/3.jpg','img/4.jpg','img/5.jpg','img/3.jpg'];
        var arr = [1,2,3,4,5,6,2];
        /*由于IE8,不支持数组的indexOf*/
        if (!Array.prototype.indexOf){  
            Array.prototype.indexOf = function(elt){  
            var len = this.length >>> 0;  
            var from = Number(arguments[1] || 0);  
            from = (from < 0)  
                 ? Math.ceil(from)  
                 : Math.floor(from);  
            if (from < 0)  
              from = 0;//如果第二个参数为负数，则按照0计算  
            for (; from < len; from++)  
            {  
              if (this[from] === elt)  //没有必要用from in this 做越界检查
               return from;  
            }  
            return -1;  
        };  
     }  
     alert(arr.indexOf(2,2));
     alert(arrImg.indexOf('img/3.jpg',2));
    };
    
</script>
</head>

<body>
</body>
</html>

 

posted on 2018-04-20 11:28  朝颜陌  阅读(162)  评论(0)    收藏  举报

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