JavaScript ReferenceError – variable is not defined
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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