JavaScript ReferenceError – variable is not defined
This JavaScript exception variable is not defined and 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.
Javascript
function sum() { let val1 = 2; let val2 = 3; return val1 + val2;}console.log(val1); |
Output:
ReferenceError: 'val1' is not defined
Example 2: In this example, the variable(GFG) is not defined, So the error has occurred.
Javascript
GFG.substring(2); |
Output:
ReferenceError: 'GFG' is not defined
