Entry

How can I create a multidimensional array?

How can I create a 2 dimensional array?

Mar 25th, 2000 17:01
Martin Honnen,

JavaScript just knows Arrays which can have arbritrary elements so if 
you need a 2 dimensional array you create an array of arrays, for three 
dimensions you create an array of arrays of arrays.
Examples on creating and accessing an array of arrays:
  // array literals (Javascript 1.2+)
  var a = [[0, 1, 2], [0, 1, 2], [0, 1, 2]];
  alert(a.length);
  alert(a[0].length);
  alert(a[0][0]);
  // Array constructor:
  var a = 
    new Array (
      new Array(0, 1, 2), new Array(0, 1, 2), new Array(0, 1, 2));
  alert(a.length);
  alert(a[0].length);
  alert(a[0][0]);
  // Populating by for loop:
  var a = new Array(3);
  for (var i = 0; i < a.length; i++) {
    a[i] = new Array(3);
    for (var j = 0; j < 3; j++)
      a[i][j] = j;
  }
  alert(a.length);
  alert(a[0].length);
  alert(a[0][0]);

Example on an array of arrays of arrays of arrays:
  var a = new Array(4);
  for (var i = 0; i < a.length; i++) {
    a[i] = new Array(4);
    for (var j = 0; j < 4; j++) {
      a[i][j] = new Array(4);
      for (var k = 0; k < 4; k++) {
        a[i][j][k] = new Array(4);
        for (var m = 0; m < 4; m++)
          a[i][j][k][m] = m;
      }
    }
  }
  alert(a);
  if (a.toSource)
    alert(a.toSource())