proxy came first and you should likely favor bind as it is a standard. The way they are called varies slightly (due to being attached to Function.prototype vs just being a function) but their behavior is the same. There is a pretty good post here: jQuery.proxy() usage, that ends with that advice.
The reason why you can access “out of scope” or “free” variables in ECMAScript is the so-called scope chain. The scope chain is a special property from each execution context. As mentioned several times before, a context object looks at least like: [[scope]] Variable / Activation Object “this” context value Each time you access a … Read more
The reason the alert shows the outdated value of count is because the callback passed to setTimeout is referencing an outdated value of count captured by the closure. This is usually referred to as a stale-closure. On the initial render, the anonymous function passed as a callback to setTimeout captures the value of count as … Read more
No, there is not. A closure is a method (a kind of function) under the hood. You are asking for the ability to exit a parent function from an arbitrarily deeply nested function call. Such non-local flow control has generally proven to be extremely bad for programmer sanity and program maintenance. To solve your problem: … Read more
Is there a god (i.e. a parent) object? Yes. More technically, it’s the global object that all these primitives are members of; it just happens that in the browser, the window object is the global object. > window.String === String; true Why is it bad idea to have vars/functions on a global level? Because if … Read more
Please have a look at closures. Delphi anonymous functions are closures. These are created within other functions and as such has access to the scope of that function. This is even so if the anonumous function is assigned to a function parameter that is called after the original function is called. (I will create an … Read more
Not really anything more than the two ways that you have proposed, but here’s another for(var it = 0; it < 2; it++) { (function() { var m = it; setTimeout(function() { alert(m); }, 1); })(); } Essentially, you need to capture the variable value in a closure. This method uses an immediately invoked anonymous … Read more
You could use a javascript closure: for (var i = 0; i < arr.length; i++) { (function(i) { // do your stuff here })(i); } Or you could just use $.each: var arr = [2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010]; $.each(arr, function(index, value) { $.ajaxSetup({ cache:false }); $.getJSON(“NatGeo.jsp”, { ZipCode: value, … Read more
The issue here is that when you close over a variable what happens behind the scenes is that the compiler creates a new unnamed type, gives that type an instance field for every variable that is closed over in that block, gives it a method for every anonymous method in that code block and then … Read more
You need to create a scope to correctly capture tmp_id using a self-executing function. That’s because the entire for loop is one scope, meaning each time through, you’re capturing the same variable. So the callback will end up with the wrong ids, because temp_id‘s value will get changed before the callback is called. I’d ignore … Read more