javascript pointer function

Question

if I have:

function init(t,y,u) 
{
   alert(t + " " + y + " " + u);
}

// String.prototype.add = init(5, 6, 7);  // 1)   
// window.onload = init(5,6,7); // 2)

in the 1) init will be executed and then it pointer assegned to String.prototype.add but in the 2) the function is only executed one time... but why not two times also when the onload event is raised?

Thanks

Konrad Rudolph · Accepted Answer · 2009-02-21 12:14:02Z

8

in the 1) init will be executed and then it pointer assegned to String.prototype.add

No it won't. The function will simply be executed and its return value (undefined) will be assigned to String.prototype.add. No function pointer will be assigned. To do this, you need to return a function!

function init(t,y,u) {
    alert(t + " " + y + " " + u);
    return function () { alert('function call!'); };
}

answered Feb 21, 2009 at 12:14

Konrad Rudolph

549k142 gold badges965 silver badges1.3k bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

some Over a year ago

To return itself: return arguments.callee;

John Smith · Accepted Answer · 2009-02-21 12:23:09Z

5

You may want something like:

String.prototype.add = function () { init(5, 6, 7); };

answered Feb 21, 2009 at 12:23

John Smith

4,5224 gold badges36 silver badges34 bronze badges

Comments

some · Accepted Answer · 2009-02-21 12:35:48Z

This is what happens with your code:

Defining a function called init with three parameters that will be alerted when the function is called.
Calling the function init with parameters 5,6,7 (an alert will popup) and assign the result (undefined) to String.prototype.add
Calling the function init with parameters 5,6,7 (an alert will popup) and assign the result (undefined) to window.onload

If the code above was executed before the window.onload event was fired, nothing will happen when it is fired, because it is set to undefined.

Collectives™ on Stack Overflow

javascript pointer function

3 Answers 3

1 Comment

Comments

Comments

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Related