What is optimal method for accessing function parameters in javascript?

Question

Of these similar function definitions, what is optimal way to access arguments and why?

function DoStuff()
{
    return arguments[0] + arguments[1] + arguments[2];
}

function DoStuff(first, second, third)
{
    return first + second + third;
}

Does one allocate less memory than the other? Is one faster to access the parameter values than the other?

Answer 1

The second.

Using the second, you know based on the signature exactly what is expected when you call the method. It's also far easier for maintainability in the future.

Answer 2

The performance difference should be fairly negligible between the two, however the readability of named parameters is a better practice. There are times when you cannot use named parameters and in those cases I typically use a big block of script to unpack arguments into named locals.

Answer 3

Forget about performance in this case and go for readability. From that perspective, option (2) is much to be preferred -- though, I'd go for more descriptive names. ;-)

Answer 4

Your junior colleague in the adjacent cube will thank you when you decide to use the latter.

Answer 5

Here is my test:

    function Test1()
    {
        var start = new Date();
        for (var i = 0; i < 1000000; i++)
        {
            DoStuff1(i, i + 1, i + 2);
        }
        var done = new Date();

        alert(done - start);
    }

    function Test2()
    {
        var start = new Date();
        for (var i = 0; i < 1000000; i++)
        {
            DoStuff2(i, i + 1, i + 2);
        }
        var done = new Date();

        alert(done - start);
    }

    function DoStuff1()
    {
        var result = arguments[0] + arguments[1] + arguments[2];
    }

    function DoStuff2(first, second, third)
    {
        var result = first + second + third;
    }

Here are the results:

IE   FF

Test1()
2355    402
2381    395
2368    392

Test2()
504  6
507  7
505  7

I figured that test 2 would be faster but it's drastically faster. So, not only is it more readable but it's more efficient.

Answer 6

Referencing arguments[] anywhere in a function will significantly decrease performance on many browsers.