Javascript object instance methods

Some other styles i've seen in the creation of instance methods on Javascript objects are as follows:

NS.test = function() {
NS.test.prototype.doSomething = function()
{
...
};
};

NS.test2 = new function() {
this.doSomething = function() {
...
};
};

(function() {
var test3 = function() {};

test3.prototype = {
doSomething : function()
{
...
}
};

NS.test3.doSomethingStatic = function() {
...
}

NS.test3 = test3;

})();

var test1 = new NS.test();
test1.doSomething();

NS.test2.doSomething();

var test3 = new NS.test3();
test3.doSomething();

NS.test3.doSomethingStatic();