javascript: how to refer to an anonymous function within the function itself?

Question

if arguments.callee is not allowed in "use strict", and we can't do

var f = function g() {
    //g
}

because in IE that wouldn't work (or that would work "weirdly") http://kangax.github.com/nfe/#jscript-bugs, then what other options do we have to refer to the anonymous function within the function itself?

This is not an anonymous function. anonymous functions don't have a handle (like `f` in your case) — neebz, Apr 22 '11 at 16:22
@nEEbz: It's the `g` that makes it not anonymous. The function in an expression `var f = function() {}`` is anonymous. — Tim Down, Apr 22 '11 at 16:54

score 5 · Answer 1 · answered Apr 22 '11 at 16:27

5

That's precisely what the Y combinator is for.

Here's an article by James Coglan about deriving the Y combinator in JavaScript.

answered Apr 22 '11 at 16:27

Jörg W Mittag

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The Y combinator seems like overkill here. – Matt Ball Apr 22 '11 at 16:35
@Matt Ball: it's a generic solution to this problem that not only works for JavaScript but for *any* language. @jamietre's solution, for example, looks basically like an idiomatic JavaScript implementation of the Y combinator with some inlining applied. I doubt you can come up with such a trick yourself if you've never heard of the Y combinator. – Jörg W Mittag Apr 22 '11 at 16:48

Matt Ball · Answer 2 · 2011-04-22T16:26:12.627

4

Don't use a named function expression. Just declare and initialize it the normal way.

function f() {
    f();
}

The only viable alternative with ES5 strict is to use the code in your question, and deal with IE's crappy NFE implementation. But: do you really expect a browser that gets NFEs so horribly wrong (ahem, IE) to implement "use strict" anytime soon?

edited Apr 22 '11 at 16:26

answered Apr 22 '11 at 16:20

Matt Ball

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@Matt Ball i may have been mistaken, but i remember reading that function declarations (the normal way) is not allowed in ES5 strict unless it is within the "global" scope.. – Pacerier Apr 22 '11 at 16:25
1

@Pacerier `[citation needed]` – Matt Ball Apr 22 '11 at 16:27
@MattBall iE10 beta has use strict in it. It's beaten chrome/safari. – Raynos Apr 22 '11 at 16:28
1

@Pacerier: [this MDC page](https://developer.mozilla.org/en/JavaScript/Strict_mode#Strict_mode_for_functions) makes me think you're remembering incorrectly. – Matt Ball Apr 22 '11 at 16:30
@Raynos did IE10 fixed this issue? – Pacerier Apr 22 '11 at 16:36
@Pacerier I don't know. I assume that named function expressions work in IE9 if they don't I'm going to get really angry. – Raynos Apr 22 '11 at 16:37
2

@Pacerier: function declarations are allowed in global or function code, but not within blocks. – Tim Down Apr 22 '11 at 16:56
@Tim which makes perfect sense _anyway_, since JS only has global and function scopes, not block scopes. – Matt Ball Apr 22 '11 at 17:00

score 1 · Answer 3 · answered Apr 22 '11 at 16:28

1

Here's a rather convoluted way to do it, but it works:

http://jsfiddle.net/4KKFN/4/

var f = function() {
    function f() {
        if (confirm('Keep going?')) {
            this.apply(this);
        }
    }
    f.apply(f);
}

f();

answered Apr 22 '11 at 16:28

Jamie Treworgy

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Can't say I'd actually use something like this in real code, but seems like a legit workaround... – Jamie Treworgy Apr 22 '11 at 16:37
Having now just read about "the Y combinator" (first I've ever heard of it) I realize, this is actually much the same thing. – Jamie Treworgy Apr 22 '11 at 16:48

javascript: how to refer to an anonymous function within the function itself?

3 Answers3