How to “properly” create a custom object in JavaScript?

Question

I wonder about what the best way is to create an JavaScript object that has properties and methods.

I have seen examples where the person used var self = this<

Answer 1

Douglas Crockford discusses that topic extensively in The Good Parts. He recommends to avoid the new operator to create new objects. Instead he proposes to create customized constructors. For instance:

var mammal = function (spec) {     
   var that = {}; 
   that.get_name = function (  ) { 
      return spec.name; 
   }; 
   that.says = function (  ) { 
      return spec.saying || ''; 
   }; 
   return that; 
}; 

var myMammal = mammal({name: 'Herb'});

In Javascript a function is an object, and can be used to construct objects out of together with the new operator. By convention, functions intended to be used as constructors start with a capital letter. You often see things like:

function Person() {
   this.name = "John";
   return this;
}

var person = new Person();
alert("name: " + person.name);**

In case you forget to use the new operator while instantiating a new object, what you get is an ordinary function call, and this is bound to the global object instead to the new object.