Glad that it helped!

Thanks

Great!

Andrew,

Thank you! And absolutely, I can relate how developers coming from C++ or similar can have a hard time with some concepts, so I hope this is helpful for those as well!

Ironically, there are many C or Java programmers that are well educated but use poor form. My C++ professor in college taught us all kinds of bad practices, like using global variables and system("PAUSE"); instead of cin.ignore(); or some other less intrusive object. JavaScript is so much easier to work with if you coming from a strong C++ background where you are mindful of C++’s built-in precautions against scope problems that are essential to OOP, because JavaScript lacks any such thing, being a loosely typed language. It’s easy to fall into sinkholes when beginning with JavaScript.

I’m begining to undertand a little more how works JavaScript.

Thank you!
Glad that it helped you as well!

I also appreciate you using an example that most of us have problem run into (where i was not what we expected, but instead was the last known value). I think that makes a big difference in helping folks to understand.

Thanks!
I’m glad that you understood it!

Thanks for explaining and for writing so much good stuff!

Thanks!

Chris,

Thank you!
The key is that the function is self-invoked, i.e. gets executed right away, and sends in the value i to be the value of num.

If you examine that part of the code more closely:

link.onclick = function (num) {
return function () {
alert(num);
};
}(i);

you can see that it is not just assigned, but actually gets called immediately by having two parentheses at the end, with i in them.

And since inner functions will always have access to their outer/containing functions’ variables (i.e. a closure is created), it will always know that num is the value of i when it was initially called.

I hope it’s clearer now!

Andrea,

Really nice!
I choose my approach partly for easier readability and understanding for everyone, but also honestly because I didn’t think as far as you did.

I think it’s a perfect example of making closures portable! Thanks!

function addLinks () {
for (var onclick = function(num){return function(){alert(num)}}, i=0, link; i<5; i++) {
link = document.createElement(”a”);
link.innerHTML = “Link ” + i;
link.onclick = onclick(i);
document.body.appendChild(link);
}
};
onload = addLinks;

This is more about performances (maniacs) but it is good to understand closure portability, isn’t it?