JavaScript Closure Example

JavaScript_Closure_Example.js

window.x = 1; // will controll external variable

(function() {

  var a = window.x / 2; // lexical scope, evaluate within external variable
  var b = window.x * 2;

  window.AAA = function A() {
    console.log(a + b); // use lexical variables
  }
})();

AAA(); // result === 2.5, as x = 1


window.x = 2; // change x = 2

AAA(); // the same result (2.5), as closure means saving lexical scope.