[removed] every event-handler defined in for-loop is the same, uses last iteration's values

Question

I have trouble understanding the scoping rules in Javascript.

In the example below, I would assume that scope url variable is private in the for-loop. And that the onloa

Answer 1

Javascript is not block-scoped, and thus requires a new function every time you want a new scope. See the answer by patrick dw.

This is why it is advantageous to use [].map(function(x){...}) or [].forEach(function(x){...}) which are in the javascript standard, since you'll need to define those functions anyway.

var imageArray = urlArray.map(function(url) {
    var image = new Image();
    image.src = url;
    image.onload = function() {
        alert(url);
    };

    return image;
});