JavaScript TypeError – Property “X” is non-configurable and can’t be deleted
Last Updated :
02 Jun, 2023
This JavaScript exception property is non-configurable and can’t be deleted if the user tries to delete a property, and the property is non-configurable.
Message:
TypeError: Calling delete on 'x' is not allowed in strict mode (Edge)
TypeError: property "x" is non-configurable and can't be deleted. (Firefox)
TypeError: Cannot delete property 'x' of #<Object> (Chrome)
Error Type:
TypeError
Cause of Error: There is an attempt to delete a property that is non-configurable.
Example 1: In this example, the delete is used to delete a non-configurable property, So the error has occurred.
Javascript
'use strict' ;
let GFG_Obj = Object.freeze({ prop1: 'val1' , prop2: 123 });
delete GFG_Obj.prop2;
|
Output(in console):
TypeError: Calling delete on 'prop2' is not allowed in strict mode
Example 2: In this example, the delete is used to delete PI which is a non-configurable property, So the error has occurred.
Javascript
'use strict' ;
delete Math.PI;
|
Output(in console):
TypeError: Calling delete on 'PI' is not allowed in strict mode
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