Anybody know how to do the same thing in JavaScript?

Thanks. I figured it out in C#. I wasn't dynamically creating the rows and didn't declare the 2d array properly.

1. Declare 2D array
2. (Dynamically) Initialize the 2D array
3. In the for loop (Dynamically) initialize the row and populate

1. public GameObject [][] pieces;

2. pieces = new GameObject[rows][];

3.

    for (int i=0; i < rows; i++) {
       pieces[i] = new GameObject[rows];
       for (int j=0; j<cols; j++){
         pieces[i][j] = (GameObject) Instantiate (gems[i], new Vector2(i,j), Quaternion.identity);

       }
    }

The line of code that's causing problems appears to assume that you can dynamically resize a builtin array.

That is not allowed.

You never declare the size of the array before you start trying to populate it.

I'm sure there are many options, but I can think of three quickly:

1. Use dynamic arrays to fill the arrays with data, then convert them to builtin arrays afterwards.
2. Declare the size of your two-dimensional, builtin array before you try to fill it with data. I don't know how to do this. I think I tried for about two seconds one day then decided there were WAY better ways to accomplish my goal.
3. Use a builtin array of dymanic arrays (see code below) to make it nice and simple.

You can read the documentation that describes the difference between builtin arrays and "javascript style" arrays here.

Here's some example code that uses a builtin array of dynamic arrays.

function populateArrayOfArrays ()
{
    var rows = 10;
    var cols = 20;

    /* declare a builtin array of 10 dynamic arrays */

    var twoDimArray : Array [] = new Array [rows]; 

    for ( var i = 0; i < rows; i ++ ) {

        /* create an new, empty array that can be resized */

        var temporaryDynamicArray = new Array();

        /* populate the temporary array */

        for ( var j = 0; j < cols; j ++ ) {
            temporaryDynamicArray.Push(generateObject(i, j));
        }

        twoDimArray[i] = temporaryDynamicArray;
    }


    /* test to see if it worked */

    for ( var r = 0; r < rows; r ++ ) {
        for ( var theItem : String in twoDimArray[r] ) {
            Debug.Log("Here's my story: " + theItem);
        }
    }
}


function generateObject ( theI, theJ ) 
{
    return "String: (" + theI + ", " + theJ + ")";
}

In my example I use an array of String arrays (rather than an array of GameObject arrays) but it shouldn't matter.

You can just replace generateObject(i, j) with a function (or code) that instantiates a GameObject.

The above example works for me: