Strict in JS code example

Example 1: javascript use strict

// Whole-Script Strict Mode Syntax
'use strict';
var v = "Hi! I'm a strict mode script!";

Example 2: use strict javascript

function doSomething() {
    'use strict';
    ...
}

Example 3: Turn on modern JS by adding use strict to your script

// Non-strict code...

(function(){
  "use strict";

  // Define your library strictly...
})();

// Non-strict code...