Question

I am new to javascript. As far as I can tell there are 5 ways to make an object (really a struct I guess). I was wondering what the best way is. Thanks.

var makeOption = function(name, dataType){
    var option = {
        name: name,
        dataType: dataType
    };
    return option;
};

var makeOption2 = function(name, dataType){ 
    this.name = name;
    this.dataType = dataType;
};

function makeOption3(name, dataType){
    this.name = name;
    this.dataType = dataType;
};

var makeOption4 = function makeOption4Name(name, dataType){
    this.name = name;
    this.dataType = dataType;
};

var v1A = makeOption("hannah", "int");
var v1B = new makeOption("hannah", "int");

//var v2A = makeOption2("hannah", "int"); <- undefined.  
var v2B = new makeOption2("hannah", "int");

// var v3A = makeOption3("hannah", "int"); <- undefined.
var v3B = new makeOption3("hannah", "int");

// var v4A = makeOption4("hannah" ,"int"); <- undefined.
var v4B = new makeOption4("hannah" ,"int");

This is what is displayed in the firebug DOM Tab:

Answer 1

Whole chapters of books on JavaScript best practices have been written on this subject. That said: If you aren’t concerned about inheritance and aren’t going to be creating numerous copies of an object with methods, i.e., you are just creating a “struct”, then object literal notation, your first example, is the way to go. In that approach, you are using object literal notation, which is lightweight and fast. It doesn’t mess with the object prototype or require the use of the new operator.

Start adding methods to your object, however, and the answer changes to “it depends.”

By the way, you left out a couple of ways to create an object:

var o = {};
o.name = "hannah";
o.dataType = "int";

and, not recommended:

var o = new Object();
o.name = "hannah";
o.dataType = "int";