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As a trivia question, I'm trying to write a javascript function that returns its variable number of arguments in sorted (normal lexicographic) order.

Having never dealt with javascript before, I came across the "arguments" object, which seems to work somewhat like an array but without having the standard array functions -- therefore I seem to need to copy its contents into a "real" array.

Is there a shorter/more concise way of doing this (preferably in a single line)?

function sortArgs() 
{
    args = new Array(); 
    for (var i = 0; i < arguments.length; i++) 
        args[i] = arguments[i]; 
    return args.sort();
}

UPDATE:
Brownie points for explaining how your answer works, since I'm new to JS. I understand slice(), but not the rest of it..

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3 Answers

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Use:

function sortArgs() 
{
    var args = Array.prototype.slice.call(arguments, 0);
    return args.sort();
}

for brownie points:

Array.prototype.slice is the slice method belonging to all instances of Array as this is coming from the prototype (or cookie cutter) of Arrays.

.call and .apply can be used to apply a function from another object as if it were a part of the object being called upon.

OtherObj.prototype.someFuntion.call(yourobject,arg1) would use yourobject as this in someFunction. You're essentially changing the context of the function.

see: https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Function/apply and https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Function/call

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Cool, thanks for the explanation. – Andrew Coleson Jun 7 at 0:42
1 
 In recent Firefox versions (2.0?) and ECMAScript 5, there's an Array.slice method that make this a little simpler. You would call it like this: var arge = Array.slice(arguments, 0);. – Matthew Crumley Jun 7 at 2:06
converting array-like objects to arrays via slice() unfortunately deson't work reliably across browsers - eg IE can't convert node lists this way; for a general function which works with all array-like objects, there's no way around manually looping over the entries – Christoph Jun 7 at 15:13
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vote up 3 vote down

If you're using jQuery, the following is a good deal easier to remember in my opinion:

function sortArgs(){
  return $.makeArray(arguments).sort();
}
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That's essentially what I was looking for in pure JS, but +1 for the solid example of how jQuery makes JS a bit easier to grok. – Andrew Coleson Jun 7 at 0:21
jquery?! the new MS – divinci Jun 7 at 1:10
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vote up 3 vote down

To golf:

function sortArgs(){ return [].slice.call(arguments).sort() }

// Returns the arguments object itself
function sortArgs(){ return [].sort.call(arguments) }

Some array methods are intentionary made not to require the target object to be an actual array. They only require the target to have a property named length and indices (which must be zero or larger integers).

[].sort.call({0:1, 1:0, length:2}) // => ({0:0, 1:1, length:2})
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Those are fun. You want to explain how they work? – Nosredna Jun 9 at 18:36
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