Javascript function as parameter to other function

Question

function addValidEvent(item,event,func)
{
 if (item.addEventListener) 
 {
 item.addEventListener(event, func, false); 
 }
 else 
 if (item.attachEvent) 
 {
 item.attachEvent("on" + event, func);
 } else {
 //todo
 }
}

I call it like

addValidEvent(element, "mouseover", inRadio(element));

inRadio this is other function, I need to register this with out call a inRadio in addValidEvent call.

How to correct pass the function like param ?

• Felix Kling: possible duplicate of javascript parameter passing in dynamic action handler

Answer 1

pass it as function. Now you are calling method inRadio. Do it like this

addValidEvent(element, "mouseover", function() {inRadio(element); });

Answer 2

The context on which your function is called is the element itself, so you could pass the function reference(name) as the event handler:

addValidEvent(element, "mouseover", inRadio);

or you can wrap your function call in an anonymous function(this might come in handy when you want to have more control over the callback) :

addValidEvent(element, "mouseover", function(){inRadio(element);});

Answer 3

In your code you are actually calling the function and the return value of that call is being passed as thrid argumnent to addValidEvent method.

Try this.

addValidEvent(element, "mouseover", inRadio);

As a side note: Since jQuery is tagged to this question I would suggest you to use jQuery for this which is so simple.

$(element).mouseover(inRadio);

Answer 4

var a = function() {
 // code here
}

Then do what you need to with 'a'

But I prefer the previous answers :)

• Felix Kling: How is this helpful? I fail to see a relation to the question.
• Felix Kling: I'd still say this is an rather incomplete example. It is not clear how a integrates with the existing code.
• Felix Kling: I did not say that ;) Anyways, I understand the problem, I just want to encourage you to improve your answer. All you show is how to create a function, which I suppose to OP already knows.