javascript remove duplicate in two arrays

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"

1array1 = array1.filter(function(val) {
2  return array2.indexOf(val) == -1;
3});
4// Or, with the availability of ES6:
5
6array1 = array1.filter(val => !array2.includes(val));
7

1// for TypeScript and JavaScript
2const initialArray = ['a', 'a', 'b',]
3finalArray = Array.from(new Set(initialArray)); // a, b

1uniqueArray = a.filter(function(item, pos) {
2    return a.indexOf(item) == pos;
3})
4