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?
Given two arrays arr1[] and arr2[], we need to combine two arrays in such a way that the combined array has alternate elements of both. If one array has extra element, then these elements are appended at the end of the combined array.
The concat() method concatenates (joins) two or more arrays. The concat() method returns a new array, containing the joined arrays. The concat() method does not change the existing arrays.
To concate two arrays, we need at least three array variables. We shall take two arrays and then based on some constraint, will copy their content into one single array. Here in this example, we shall take two arrays one will hold even values and another will hold odd values and we shall concate to get one array.
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 ([], [])) // [ ]
And another variation that supports any number of input arrays -
const interleave = ([ x, ...xs ], ...rest) =>
x === undefined
? rest.length === 0
? [] // base: no x, no rest
: interleave (...rest) // inductive: no x, some rest
: [ x, ...interleave(...rest, xs) ] // inductive: some x, some rest
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 ([], [])) // [ ]
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With