getElementByIdx_x js自定义getElementById函数

document.getElementByIdx_x=function(id){ 
if(typeof id =='string') 
return document.getElementById(id); 
else 
throw new error('please pass a string as a id!') 
} 
 
实例代码: 
 代码如下:

<div id='box'>9</div> 
<script> 
document.getElementByIdx_x=function(id){ 
if(typeof id =='string') 
return document.getElementById(id); 
else 
throw new error('please pass a string as a id!') 
} 
var timer = window.setInterval(function(){ 
document.getElementByIdx_x('box').innerHTML = parseInt(document.getElementByIdx_x('box').innerHTML) - 1; 
if(parseInt(document.getElementByIdx_x('box').innerHTML) < 0) 
{ 
window.clearInterval(timer); 
window.location = '//www.gxlcms.com'; 
} 
}, 1000); 
</script>