'use strict' in javascript

Question

What is difference ? and why this ?

Answer 1

"use strict"; Defines that JavaScript code should be executed in "strict mode".

Declaring Strict Mode

Strict mode is declared by adding "use strict"; to the beginning of a script or a function.

Declared at the beginning of a script, it has global scope (all code in the script will execute in strict mode):

Example

"use strict";
x = 3.14;       // This will cause an error because x is not declared

CREDIT - https://www.w3schools.com/js/js_strict.asp

This website will help you - https://www.w3schools.com/js/js_strict.asp