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I am quite new with Javascript and I got a problem with document.getElementById() that always returns NULL, and that's driving me nuts.
I have a element in my code and I want to get its coordinates so I can move it.
Here is the code:
<html>
<head>
<script type="text/javascript" >
function MoveIt(obj) {
alert(obj); // returns "Object HTMLDivElement"
var xx = document.getElementById("arect");
if(document.getElementById("arect").value == null) {
alert('NULL >> ' + xx.value);
}
else {
alert('NOT NULL >>' + xx.value);
}
posX = xx.style.scrollTop;
posY = xx.style.left;
}
</script>
</head>
<body bgcolor="white" >
<DIV class="background" id="MyDiv2">
<div id="arect" name="arect" class="transbox" onmousedown="MoveIt(this);" >
</div>
</div>
</body>
</html>
The above function MoveIt() always returns NULL
549
The getElementById() method returns null if the element does not exist. The getElementById() method is one of the most common methods in the HTML DOM.
To solve the "getElementById is not a function" error, make sure to spell the getElementById() method correctly, as it is case-sensitive, and only call the method on the document object, e.g. document. getElementById('btn') . Copied!
The Document method getElementById() returns an Element object representing the element whose id property matches the specified string. Since element IDs are required to be unique if specified, they're a useful way to get access to a specific element quickly.
The page contents need to be loaded before trying to read them. Try
window.onload = function() {
// run your script in here
}
Or if you're using jQuery, prefer
$(document).ready(function() {
...
}
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