自定义$()函数出错

godxiaocao 2012-11-13 05:46:31

<!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=utf-8" />

<title>无标题文档</title>

</head>

<script>

var simple = function(){

	this.getId = function(elementId){

		var element = document.getElementById(elementId);

		//alert(elementId);

		return element;

	}

}



var $ = function(string){

	var sim = new simple();

	var start = string.indexOf("#");

	if(start != -1)

	{

		start += 1;

		var str = string.substring(start);

		return sim.getId(str);

	}

	else

	{

		return null;

	}

}



alert($("#e"));

</script>

</head>



<body>

<input type="text" id="e" value="1234" />

</body>

</html>

怎么返回不了ID为e的DOM对象的?
我哪里出错了?

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wu_now 2012-11-14

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学习了，楼上的朋友们真是太给力了！！

godxiaocao 2012-11-13

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楼上门正解....

ChinaXtHuLang 2012-11-13

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引用 1 楼 likeajin 的回复:

在你获取dom时dom未加载。 XML/HTML code? 12345678910111213141516171819202122232425262728293031323334353637383940 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/……

+1 或：

<!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=utf-8" /> 
<title>无标题文档</title> 
</head> 
<script> 
var simple = function(){ 
    this.getId = function(elementId){ 
        var element = document.getElementById(elementId); 
        //alert(elementId); 
        return element; 
    } 
} 
  
var $ = function(string){ 
    var sim = new simple(); 
    var start = string.indexOf("#"); 
    if(start != -1) 
    { 
        start += 1; 
        var str = string.substring(start); 
        return sim.getId(str); 
    } 
    else 
    { 
        return null; 
    } 
} 


</script> 
</head> 
  
<body> 
<input type="text" id="e" value="1234" /> 
<script type="text/javascript">
(function() {
    alert($("#e"));
})();
</script>
</body> 
</html>

likeajin 2012-11-13

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在你获取dom时dom未加载。


<!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=utf-8" />
<title>无标题文档</title>
</head>
<script>
var simple = function(){
    this.getId = function(elementId){
        var element = document.getElementById(elementId);
        //alert(elementId);
        return element;
    }
}
 
var $ = function(string){
    var sim = new simple();
    var start = string.indexOf("#");
    if(start != -1)
    {
        start += 1;
        var str = string.substring(start);
        return sim.getId(str);
    }
    else
    {
        return null;
    }
}
 
//alert($("#e"));
window.onload=function(){alert($("#e"));}
</script>
</head>
 
<body>
<input type="text" id="e" value="1234" />
</body>
</html>