1const names = ['John', 'Paul', 'George', 'Ringo', 'John'];
2
3let unique = [...new Set(names)];
4console.log(unique); // 'John', 'Paul', 'George', 'Ringo'

1let arr = [1,2,3,1,1,1,4,5]
2    
3let filtered = arr.filter((item,index) => arr.indexOf(item) === index)
4    
5 console.log(filtered) // [1,2,3,4,5]

1// 1. filter()
2function removeDuplicates(array) {
3  return array.filter((a, b) => array.indexOf(a) === b)
4};
5// 2. forEach()
6function removeDuplicates(array) {
7  let x = {};
8  array.forEach(function(i) {
9    if(!x[i]) {
10      x[i] = true
11    }
12  })
13  return Object.keys(x)
14};
15// 3. Set
16function removeDuplicates(array) {
17  array.splice(0, array.length, ...(new Set(array)))
18};
19// 4. map()
20function removeDuplicates(array) {
21  let a = []
22  array.map(x => 
23    if(!a.includes(x) {
24      a.push(x)
25    })
26  return a
27};
28/THIS SITE/ "https://dev.to/mshin1995/back-to-basics-removing-duplicates-from-an-array-55he#comments"

1const numbers = [1 , 21, 21, 34 ,12 ,34 ,12];
2const removeRepeatNumbers = array => [... new Set(array)]
3removeRepeatNumbers(numbers) // [ 1, 21, 34, 12 ]

1function toUniqueArray(a){
2    var newArr = [];
3    for (var i = 0; i < a.length; i++) {
4        if (newArr.indexOf(a[i]) === -1) {
5            newArr.push(a[i]);
6        }
7    }
8  return newArr;
9}
10var colors = ["red","red","green","green","green"];
11var colorsUnique=toUniqueArray(colors); // ["red","green"]

1function onlyUnique(value, index, self) {
2  return self.indexOf(value) === index;
3}
4
5// usage example:
6var a = ['a', 1, 'a', 2, '1'];
7var unique = a.filter(onlyUnique);
8
9console.log(unique); // ['a', 1, 2, '1']