This is the basic library structure (it is following modular pattern)

RjLibBasic.js

var RjLib = (function RjLib() {
  var _helloText = 'Hello world';
  /*
  ** This constructor can be annoynomus  
  ** or it can have function name
  */
  // Return the constructor
  return function(){
      var _this = this; // Cache the `this` keyword
      
      // returning public function
      _this.hello = hello;
  };
  
  function hello() {
      return _helloText; // Access a private variable
  }
}());

var myLib = new RjLib(); // invoke