Split a string into a 2 level multidimensional array

Take one string then split it into a 2 layer multidimensional array

JavaScript

var str = "1,2,3|4,5,6|7,8,9|11,21,31";
var tempArray = str.split('|');
var finalArray = [];
for (var i = 0; i < tempArray.length; i++) {
    finalArray[i][ = tempArray[i].split(',');
}
document.write("Final array has " + finalArray.length + " nodes!");