how to access 2D array in javascript code example

Example 1: how to read 2 dimensional array in javascript

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

Example 2: javascript define 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;
 }
}