JavaScript TypeError – Invalid assignment to const “X”
Last Updated :
31 Jul, 2020
This JavaScript exception invalid assignment to const occurs if a user tries to change a constant value. Const declarations in JavaScript can not be re-assigned or re-declared.
Message:
TypeError: invalid assignment to const "x" (Firefox)
TypeError: Assignment to constant variable. (Chrome)
TypeError: Assignment to const (Edge)
TypeError: Redeclaration of const 'x' (IE)
Error Type:
TypeError
Cause of Error: A const value in JavaScript is changed by the program which can not be altered during normal execution.
Example 1: In this example, the value of the variable(‘GFG’) is changed, So the error has occurred.
HTML
< script >
const GFG = "This is GFG";
// Error here
GFG = "This is GeeksForGeeks";
</ script >
|
Output(in console):
TypeError: Assignment to const
Example 2: In this example, the value of the object(‘GFG_Obj’) is changed, So the error has occurred.
HTML
< script >
const GFG_Obj = {key: 'val1'};
// Error here
GFG_Obj = {key: 'val2'};
</ script >
|
Output:
TypeError: Assignment to const
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