Alternative to arguments.callee

Question

I have an EventListener that listens to the entire document and records keystrokes, but I want to remove this Listener when certain conditions are met.

The following is a snippet of my code:

document.addEventListener('keyup', function(e) {
    var letter_entered = String.fromCharCode(e.keyCode).toLowerCase();
    player.makeGuess(letter_entered);

    if(player.win_status === true || player.lose_status === true) {
        document.removeEventListener('keyup', arguments.callee, false);
    }
});

This works, however according to the Mozilla Developer Docs this method has been deprecated.

I'm aware that I can simply name the function, but is there an alternative that would allow me to continue using the unnamed function?

No. You have to store a reference to it somehow, like `arguments.callee` does. — Joe Simmons, Oct 06 '13 at 23:09
@user2736012 Question is more out of curiosity than practical use. — MitulP91, Oct 06 '13 at 23:12
No, there's no other way other than to use a variable reference to an anonymous function. If there was, it would just be redundant. — user2736012, Oct 06 '13 at 23:13
possible duplicate of [Arguments.callee is deprecated - what should be used instead?](http://stackoverflow.com/questions/8361642/arguments-callee-is-deprecated-what-should-be-used-instead) — DavidRR, Jun 18 '15 at 19:24

score 14 · Answer 1 · edited Jan 28 '15 at 17:07

14

Use the following process:

Create a variable
Assign an anonymous function to the variable
Invoke it with the variable reference
The anonymous function references itself using the variable name

Use it as such:

   var foo = function(e)
    {
    "use strict";
    console.log(e);
    document.removeEventListener('keyup', foo, false);
    }

document.addEventListener('keyup', foo);

You can solve this problem easily using the y combinator:

function y(f) {
    return function () {
        return f.bind(null, y(f)).apply(this, arguments);
    };
}

Now you can rewrite your code as follows:

document.addEventListener("keyup", y(function (callee, e) {
    player.makeGuess(String.fromCharCode(e.keyCode).toLowerCase());
    if (player.win_status || player.lose_status) document
        .removeEventListener("keyup", callee);
}));

That's all folks.

edited Jan 28 '15 at 17:07

Paul Sweatte

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answered Dec 06 '13 at 07:33

Aadit M Shah

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Is this different from `function y(f) { return function yf() { return f.bind(null, yf).apply(this, arguments)`? – Oct 22 '14 at 18:34
Yes, but the entire point of the OP's question is not to use named functions. – Aadit M Shah Oct 22 '14 at 19:23
2

Cool stuff but it doesn't answer the question which is in the title. In fairness, the title is wrong. :) But I was actually looking for the answer to a generic alternative for `arguments.callee` and this isn't it. – Stijn de Witt Apr 17 '17 at 20:18
Javascript is such a weird language, thanks for this solution! I didn't know it was possible to do that. – rez Mar 11 '20 at 15:21

Paul Sweatte · Answer 2 · 2015-01-22T17:08:43.063

Use another anonymous function as a wrapper to store a named function (callee shim) to your original function:

document.addEventListener('keyup', (function(e)
  {
  var aFunction = function()
    {
    var letter_entered = String.fromCharCode(e.keyCode).toLowerCase();
    player.makeGuess(letter_entered);
    };

  if(player.win_status === true || player.lose_status === true) 
    {
    document.removeEventListener('keyup', window, false);
    }
  else
    {
    aFunction();
    }
  }
), false);

References

Alternative to arguments.callee

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