Check if a variable has been assigned a value in JavaScript
Description
The following code shows how to check if a variable has been assigned a value.
Example
<!--from www .ja va2 s . com-->
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
var aString = null;
if(aString == null){
document.writeln("Not assigned");
}
aString = "some value";
if(aString == null){
document.writeln("Not assigned");
}else{
document.writeln("Assigned");
}
</script>
</head>
<body>
</body>
</html>
The code above generates the following result.
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