javascript multidimensional array

var iMax = 20;
var jMax = 10;
var f = new Array();

for (i=0;i<iMax;i++) {
 f[i]=new Array();
 for (j=0;j<jMax;j++) {
  f[i][j]=0;
 }
}

var arr = [
   ["one", "two", "three"],
   [4, 5, 6],
   ["seven", 8, "nine"],
   [10, "eleven", 12],
];

// So to access '8' 3rd row, second column (just minus 1)
arr[2][1];

        
            
        
     activities.forEach((activity) => {
    activity.forEach((data) => {
        console.log(data);
    });
});

var array = [
  ["0, 0", "1, 0", "2, 0", "3, 0", "4, 0"],
  ["0, 1", "1, 1", "2, 1", "3, 1", "4, 1"],
  ["0, 2", "1, 2", "2, 2", "3, 2", "4, 2"],
  ["0, 3", "1, 3", "2, 3", "3, 3", "4, 3"],
  ["0, 4", "1, 4", "2, 4", "3, 4", "4, 4"],
  ]; // Think of it as coordinates, array[x, y] x = 0; y = 0; is "0, 0" on 
	// this grid

console.log(array[3][3]); // returns "3, 3"
// If you use graphics (ex: p5js or JS Canvas) then this will be a 5x5 map.
// Useful for roguelikes and/or raycasters.

var items = [
  [1, 2],
  [3, 4],
  [5, 6]
];
console.log(items[0][0]); // 1
console.log(items[0][1]); // 2
console.log(items[1][0]); // 3
console.log(items[1][1]); // 4
console.log(items);

<script type="text/javascript">
var myObj = { 
    fred: { apples: 2, oranges: 4, bananas: 7, melons: 0 }, 
    mary: { apples: 0, oranges: 10, bananas: 0, melons: 0 }, 
    sarah: { apples: 0, oranges: 0, bananas: 0, melons: 5 } 
}

document.write( myObject[ 'fred' ][ 'apples' ] );