This JavaScript exception variable is not defined occurs if there is a non-existent variable that is referenced somewhere.
Message:
ReferenceError: "x" is not defined
Error Type:
ReferenceError
Cause of Error:
There is a non-existent variable that is referenced somewhere in the script. That variable has to be declared, or make sure the variable is available in the current script or scope.
Example 1: In this example, the variable(val1) is being accessed from the outside of the function, So the error has not occurred.
HTML
<script>
function sum() {
var val1 = 2;
var val2 = 3;
return val1 + val2;
}
document.write(val1);
</script>
|
Output:
ReferenceError: 'val1' is not defined
Example 2: In this example, the variable(GFG) is not defined, So the error has occurred.
HTML
<script>
GFG.substring(2);
</script>
|
Output:
ReferenceError: 'GFG' is not defined
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