useStrict in javascript
In this article,we are using a useStrict mode by putting strictmode on first line or with some function.
1'use strict';In non strict variable,undeclared variable creates a global variable for example :
1function sloppyFunc() {
2 undeclaredVar1 = 123;
3}
4sloppyFunc();
5// Created global variable undeclaredVar1:
6assert.equal(undeclaredVar1, 123);The functions shows an error when it is called
1function strictFunc() {
2'use strict';
3undeclaredVar2 = 123;
4}
5assert.throws(
6() => strictFunc(),
7{
8name: 'ReferenceError',
9message: 'undeclaredVar2 is not defined',
10});
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