Flatten an array

flattenArray.js

function flattenMyArr(nArr) {
  for (let i = 0; i < nArr.length; i++) {
    if (Array.isArray(nArr[i])) {
      flattenMyArr(nArr[i])
    } else {
      flatArr.push(nArr[i])
    }
  }
  return flatArr;
}

var flatArr = [];
var p = [[1, 2, [3]], 4];
var q = flattenMyArr(p);

console.log(q);