Populating a 2D array in Javascript with random numbers

Question

I\'m trying to populate a 2D array in javascript with random numbers. Although each column in the array is random, each row is identical which is not what I want (see image bel

Answer 1

This can be accomplished using a combination of Array.prototype.fill() and Array.prototype.map():

new Array(rows).fill([]).map(x => Array(columns).fill(0).map(x => x + Math.floor(Math.random() * (max - min)) + min));

For example, we can create a 100 by 964 column array full of random numbers between 900 and 1000 using the following:

new Array(100).fill([]).map(x => Array(964).fill(0).map(x => x + Math.floor(Math.random() * (1000 - 900)) + 900));

Answer 2

The trouble is that you're not initializing the row. It's easily fixed:

cols = 5;
rows = 10;

front = new Array(cols)// .fill(new Array(rows));

// Loop through Initial array to randomly place cells
for(var x = 0; x < cols; x++){
  front[x] = [];  // ***** Added this line *****
  for(var y = 0; y < rows; y++){
    front[x][y] = Math.floor(Math.random()*5);
  }
}
console.table(front) ; // browser console only, not StackOverflow's

Update

This is a cleaner version, somewhat similar to the one from Code Maniac, but simplified a bit:

const randomTable = (rows, cols) => Array.from(
  {length: rows}, 
  () => Array.from({length: cols}, () => Math.floor(Math.random() * 5))
)

console.table(randomTable(10, 5)) // browser console only, not StackOverflow's

Answer 3

One way of doing this using map

let op = new Array(10)
         .fill(0)
         .map(e=>(new Array(5)
         .fill(0)
         .map(e=> Math.floor(Math.random() * 5))))

console.log(op)