JavaScript; n-dimensional array creation

There's nothing built in, but it's pretty easy to create a function that would do the job:

var genArray = function () {
    var arr, len, i;
    if(arguments.length > 0) {
        len = [].slice.call(arguments, 0, 1)[0];
        arr = new Array(len);
        for(i = 0; i < len; i++) {
            arr[i] = genArray.apply(null, [].slice.call(arguments, 1));
        }
    } else {
        return null; //or whatever you want to initialize values to.
    }
    return arr;
};

var a = genArray(3, 2); //is [[null, null],[null, null],[null, null]]
var b = genArray(3, 1, 1); //is [[[null]],[[null]],[[null]]]

a[0][1]; //is null
b[1][0][0]; //is null
b[1][0][0] = 3;
b[1][0][0]; //is 3;
b; //is [[[null]],[[3]],[[null]]]

Maybe that will help?

PS --

I know this might seem like more effort than is necessary. But unfortunately, JavaScript arrays are not really "arrays" (if by "array" you mean a contiguous, indexed, immutable memory block). They're more like "maps" in most languages. So there's a certain amount of effort involved in creating them. Most languages have no problem creating multi-dimensional arrays because they're just doing some simple multiplication followed by an malloc(). But with JavaScript, you really have to go recursively generate your arrays if you want to have them pre-constructed. It's a pain, but it does demonstrate the effort required by the interpreter.

Go figure.

Tested in Chrome:

function createNDimArray(dimensions) {
    if (dimensions.length > 0) {
        var dim = dimensions[0];
        var rest = dimensions.slice(1);
        var newArray = new Array();
        for (var i = 0; i < dim; i++) {
            newArray[i] = createNDimArray(rest);
        }
        return newArray;
     } else {
        return undefined;
     }
 }

Then createNDimArray([3, 2, 5]) returns a 3x2x5 array.

You can use a similar recursive procedure to access an element whose index is in an array:

function getElement(array, indices) {
    if (indices.length == 0) {
        return array;
    } else {
        return getElement(array[indices[0]], indices.slice(1));
    }
 }

Setting an element is similar, and left as an exercise for the reader. 

For creating an n-dimensional array:

function createNDimArray(dimensions) {
 var ret = undefined;
 if(dimensions.length==1){
    ret = new Array(dimensions[0]);
    for (var i = 0; i < dimensions[0]; i++)
        ret[i]=null; //or another value
    return ret;     
 }
 else{
    //recursion
    var rest = dimensions.slice(1);
    ret = new Array(dimensions[0]);
    for (var i = 0; i < dimensions[0]; i++)
        ret[i]=createNDimArray(rest);       
    return ret;
 }
}