initialize2DArray javascript Code Snippet in 2025

Initializes a 2D array of given width and height and value.

• Use Array.from() and Array.prototype.map() to generate h rows where each is a new array of size w.
• Use Array.prototype.fill() to initialize all items with value val.
• Omit the last argument, val, to use a default value of null.

const initialize2DArray = (w, h, val = null) =>
  Array.from({ length: h }).map(() => Array.from({ length: w }).fill(val));

initialize2DArray(2, 2, 0); // [[0, 0], [0, 0]]