Make a chunk of fixed size of a linear array.

arrayChunk.js

/**
 * Create chunk using a fixed size.
 *
 * @author Sajeeb Ahamed
 * @see https://stackoverflow.com/a/61413202/4610740
 */

// Add the chunk function into the array prototype.
Array.prototype.chunk = function(size) {
  
  // Make a clone of the main array as the main array being untouched.
  let data = [...this];  
  let result = [];
  
  // Splice the array until it's not being empty.
  while(data.length) {
      result.push(data.splice(0, size));
  }

  return result;
}

const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];
const chunked = arr.chunk(2);

console.log(chunked);
// Output: [[1, 2], [3, 4], [5, 6], [7, 8], [9]]