What the difference between those two?

Question

Is there any difference between these two:

var test1 = function () {
    this.method1 = function() {}
}

and

var test2 = function() {};
test2.method1 = function() {};

Answer 1

The first snippet takes this object, whatever it is, and assigns a function to its slot (field) named method1. this can represent different objects, depending upon how test1 is called:

• when called as a standalone function -- test1() -- this will be window
• when called as a constructor -- new test1() -- this refers to the object being created
• when called via call or apply -- test1.apply(someObject) -- this refers to the argument

The second snippet takes the object test2 and assigns a function to its slot named method1.

Answer 2

The first way is a constructor that creates more objects and needs to have the new keyword:

var mytest1 = new test1();
mytest1.method1();

The second way is ready to use right away:

test2.method1();