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Created May 28, 2020 15:48
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3 Ways to get unique values from an array in Javascript
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unique-array-values-js.md

Here are 3 ways to retrieve unique values from arrays in Javascript

  1. The array.filter method which is a higher order function which means it takes a function as it's argument.
const someArray = ['😁', '💀', '💀', '💩', '💙', '😁', '💙'];

const getUniqueValues = (array) => (
  array.filter((currentValue, index, arr) => (
		arr.indexOf(currentValue) === index
	))
)

console.log(getUniqueValues(someArray))
// Result ["😁", "💀", "💩", "💙"]
  1. The array.reduce method which is a higher order function which means it takes a function as it's argument.
const someArray = ['😁', '💀', '💀', '💩', '💙', '😁', '💙'];

const getUniqueValues = (array) => (
  array.reduce((accumulator, currentValue) => (
    accumulator.includes(currentValue) ? accumulator : [...accumulator, currentValue]
  ), [])	
)

console.log(getUniqueValues(someArray))
// Result ["😁", "💀", "💩", "💙"]
  1. Using the Set method.
const someArray = ['😁', '💀', '💀', '💩', '💙', '😁', '💙'];

const getUniqueValues = (array) => (
	[...new Set(array)]
)

console.log(getUniqueValues(someArray))
// Result ["😁", "💀", "💩", "💙"]
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