Functional JavaScript — Functional Array Methods

Concatenating and zipping arrays.

JavaScript is partly a functional language.

To learn JavaScript, we got to learn the functional parts of JavaScript.

In this article, we’ll look at how to create our own array methods.

concatAll

We can create our own concatAll method to concatenate all the nested array into one big array.

For example, we can write:

const concatAll = (arrays) => {
  let results = []
  for (const array of arrays) {
    results = [...results, ...array];
  }
  return results;
}

We just spread the array entries of all the arrays and then return the resulting array.

Then we can use it to unnest nested arrays.

For example, we can write:

const arr = concatAll([
  [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9]
]);

Then arr is:

[1, 2, 3, 4, 5, 6, 7, 8, 9]

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