js test

js-test.js

var a = (function () {
    this.x = 100;
    var a = 1;

    var showX = function () {
        console.log(this.x);
    };

    var setX = function () {
        this.x = -100;
    };

    showX(); // 100

    return {
        a : a,
        setX : setX,
        showX : showX
    };
})();

console.log(a.x); // undefined
a.setX();
console.log(a.x); // -100