Javascript dynamically judges HTML elements and performs different actions

In javascript, in order to perform different operations on different elements, you need to judge the element that triggers the event in javascript and then perform different operations.

Example:

HTML

 
<input type='button' name = 'updatemetal' value=' Modify the ' onclick='getmetalid(this)'> 
<input type='button' name = 'deletemetal' value=' delete ' onclick='getmetalid(this)'> 

javascript

 
<script type="text/javascript"> 
function getmetalid(input) { 
metalid = input.parentNode.parentNode.firstChild.innerHTML; 
if(input.getAttribute("value") == ' Modify the '){ 
damicsubmit(metalid); 
}else if(input.getAttribute("value") == ' delete '){ 
damicsubmit2(metalid); 
} 
} 
</script> 

The name and id attributes of input were not successfully obtained, but the value was ok. I don't know why.

Reference:

 
var obj=document.getElementById("div1").getElementsByTagName("textarea") 
for(var i=0;i<obj.length;i++) 
{ 
if(obj[i].id=="aa") 
{ 
alert(obj[i].innerText) 
} 
}