javascript - Merge two arrays with alternating values

Question

I would like to merge 2 arrays with a different length:

let array1 = ["a", "b", "c", "d"];
let array2 = [1, 2];

The outcome I would expect is ["a", 1 ,"b", 2, "c", "d"]

What's the best way to do that?

Answer 1

Here's another way you can do it using destructuring assignment -

const interleave = ([ x, ...xs ], ys = []) =>
  x === undefined
    ? ys                             // base: no x
    : [ x, ...interleave (ys, xs) ]  // inductive: some x
        
console.log (interleave ([0, 2, 4, 6], [1, 3, 5])) // [ 0 1 2 3 4 5 6 ]    
console.log (interleave ([0, 2, 4], [1, 3, 5, 7])) // [ 0 1 2 3 4 5 7 ]
console.log (interleave ([0, 2, 4], []))           // [ 0 2 4 ]
console.log (interleave ([], [1, 3, 5, 7]))        // [ 1 3 5 7 ]
console.log (interleave ([], []))                  // [ ]