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Zip two arrays repeating values of the smaller one

So, we have two arrays and we need map each element of the first array to an element from the second. The length of the second array may be less or equal than the first one. What’s if we need to repeat values of the smaller one?

For example, there are two arrays:

const numbers = [1, 2, 3, 4, 5, 6, 7, 8]
const letters = ['a', 'b', 'c']

And we need to get something like:

[ { number: 1, letter: 'a' },
  { number: 2, letter: 'b' },
  { number: 3, letter: 'c' },
  { number: 4, letter: 'a' },
  { number: 5, letter: 'b' },
  { number: 6, letter: 'c' },
  { number: 7, letter: 'a' },
  { number: 8, letter: 'b' } ]

You can use Google or your math skills 😎 and finally will come to this:

const getNormalizedIndex = (index, array) => ((index + array.length) % array.length) % array.length

const numbers_letters = numbers.map((item, index) => {
  return {
    number: item,
    letter: letters[getNormalizedIndex(index, letters)]
  }
})

Run it and you’ll get the expected result.

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