remove duplicate elements from an array in javascript

remove_duplicates.js

arr = [5, 1, 3, 1, 4, 4, 5]

// using Set
/* Set is a new data structure introduced in ES6 which contains only unique elements */
unique_arr = [...new Set(arr)]
// expanding the process
a_set = new Set(arr) // {5, 1, 3, 4}
unique_arr = Array.from(a_set) //[5, 1, 3, 4]

// using filter
unique_arr = arr.filter((ele, index) => arr.indexOf(ele) === index)
// indexOf returns first index of the element occurance, hence it will all the elements

//using reduce
unique_arr = arr.reduce((unique, ele) => unique.includes(ele) ? unique : [...unique, ele], [])
/* reduce function reduces a given array on the basis of some function passed,
Here, we are initializing a unique array whose initital value is []. Adding elements
one by one, by checking is that element already present in the array(unique) or not.*/