JavaScript SyntaxError – Applying the ‘delete’ operator to an unqualified name is deprecated
This JavaScript exception applying the ‘delete’ operator to an unqualified name is deprecated works in strict-mode and it occurs if variables are tried to be deleted with the delete operator.
Message:
SyntaxError: Calling delete on expression not allowed
in strict mode (Edge)
SyntaxError: applying the 'delete' operator to an unqualified name
is deprecated (Firefox)
SyntaxError: Delete of an unqualified identifier in strict mode.
(Chrome)
Error Type:
SyntaxError
Cause of Error: In strict mode, trying to delete a variable will throw an error and is not permitted. Normal variables in JavaScript can’t be deleted with help of the delete operator.
Example 1:
HTML
<!DOCTYPE html><html><head> <title>Syntax Error</title></head><body> <script> 'use strict'; var GFG ="This is GeeksforGeeks"; document.write(GFG); GFG = null; </script></body></html> |
Output:
This is GeeksforGeeks
Example 2: In this example, delete operator is used which causes the error.
HTML
<!DOCTYPE html><html><head> <title>Syntax Error</title></head><body> <script> 'use strict'; var GFG ="This is GeeksForGeeks"; document.write(GFG); delete GFG; </script></body></html> |
Output(in console):
SyntaxError: Delete of an unqualified identifier in strict mode.
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