Flatten the Array

by Pritesh Patel

JavaScript

function flatten(arr) {
  return arr.reduce(function (flat, toFlatten) {
    return flat.concat(Array.isArray(toFlatten) ? flatten(toFlatten) : toFlatten);
  }, []);
}
console.log(flatten([[[1,[1.1]], 2, 3], [4, 5]]));