Uncaught TypeError: Cannot set property '0' of undefined on 2D array (JavaScript)

Question

I am try to set value get from String into 2D-Array.

But it does not work. error description in the picture.

My code:

data = "012021111"
function isGameOver(data){
var map = [[],[]];
var index = 0;
    for (var i = 0; i < 3; i++) {
        for (var j = 0; j < 3; j++) {
            map[i][j] = data[index];
            console.log("index: " +index+ ",i: " + i + ",j: " + j + ", data: " + map[i][j]);
            index++;             
        }            
    }        
 }

Answer 1

error in your code is because you initialize map = [[], []] that is map is an array containing two elements only which are again arrays. But you are trying to access map[2] which is undefined. A better solution would be to initialize map as an empty array and inside first for loop push arrays to map as required.

 data = "012021111" function isGameOver(data){ var map = []; var index = 0; for (var i = 0; i < 3; i++) { map.push([]); for (var j = 0; j < 3; j++) { map[i][j] = data[index]; console.log("index: " +index+ ",i: " + i + ",j: " + j + ", data: " + map[i][j]); index++; } } } isGameOver(data);