Array flatten function written in ES6 syntax

flatten-array.js

function flat(array, depth = 1) {
  let result = [];
  if (depth !== 1) {
    result = array;
    for (let i = 0; i < depth; i++) {
      result = flat(result);
    }
    return result;
  }
  for (let element of array) {
    if (Array.isArray(element)) {
      if (element.length > 0) { // we don't want to go in the else if the array is empty
        for (let subElement of element) {
          result.push(subElement);
        }
      }
    }
    else {
      result.push(element);
    }
  }
  return result;
}