In the below code

(function x() {
var j = function() { alert("234234"); }
return {
    s: j
}
})()

var x1 = new x();
x1.s();

How to invoke the method j()? Or before that i should be asking, is there a way to create an instance of the function x() because that is what is happening. Please see the fiddle /

In the below code

(function x() {
var j = function() { alert("234234"); }
return {
    s: j
}
})()

var x1 = new x();
x1.s();

How to invoke the method j()? Or before that i should be asking, is there a way to create an instance of the function x() because that is what is happening. Please see the fiddle http://jsfiddle/e5k6bdvn/

• javascript
• self-invoking-function

• 1 Why do you have it like that to begin with? That pattern does not make sense. – epascarello Commented Jan 23, 2015 at 18:14
• 1 You code is very odd. You seem to have built something following the module pattern (except you used a named function), and then you invoke the function that should only be self-invoked again but as if it was a constructor function (which it definitely isn't designed to be) – Quentin Commented Jan 23, 2015 at 18:18
• True! you caught that. the whole idea is not to make it a constructor function. but rather am trying to find a way to invoke method j inside it. By the way, self invoking functions cannot be a constructor function?? – maze star Commented Jan 23, 2015 at 18:20
• It makes no sense to write a self-invoking constructor function. Constructor functions are good for creating multiple instances of an object type. Self-invoking functions are good for creating singletons. – Quentin Commented Jan 23, 2015 at 18:21
• Allrite, I get the point. My question still remains unanswered. Can self invoking functions be a constructor function? since i am getting error while creating an instance. – maze star Commented Jan 23, 2015 at 18:24

2 Answers 2

1. Don't give the self invoking function a name (there is little benefit to it beyond making it easier to find in a stacktrace, which you shouldn't need at that point, and it memory leaks in old IE)
2. Don't call the self invoking function twice
3. Don't treat the self invoking function as if it was a constructor function (by calling it with new)
4. Do capture the return value of the self-invoking function

Such:

    var x = (function () {
        var j = function() { alert("234234"); };
        return {
            s: j
        };
    })();
    
    x.s();

Or, if you want to create multiple objects in the same way:

1. Don't use a self-invoking function
2. Do call x as many times as you like

Such:

    function x () {
        var j = function() { alert("234234"); };
        return {
            s: j
        };
    };

    var x1 = x();
    var x2 = x();
    x1.s();

Or, if you want to create a constructor function:

1. Don't return anything from it
2. Do use the prototype chain

Such:

    function x () {
    };

    x.prototype.s = function () {
        alert("234234");
    }
    
    var x1 = new x();
    var x2 = new x();
    x1.s();

As stated by @epascarello, it's hard to say what is the context of your question.

If the meaning of x is to return objects more than once, you should not immediately invoke it. Instead you need only to declare it:

function x () { return { j: function () { alert("234234") } } }

then call it whenever you want, and invoke j.

var x1 = x();
x1.j();

If instead you're planning to use x only once, it's nice to invoke it immediately, but you need to consume the call to j immediately too.

(function () {
    return {
        j: function () {
            alert("234234")
        }
    }
})().j();