javascript remove duplicate strings from array

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

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"

1unique = [...new Set(arr)];   // where arr contains duplicate elements

1const names = ['John', 'Paul', 'George', 'Ringo', 'John'];
2
3function removeDups(names) {
4  let unique = {};
5  names.forEach(function(i) {
6    if(!unique[i]) {
7      unique[i] = true;
8    }
9  });
10  return Object.keys(unique);
11}
12
13removeDups(names); // // 'John', 'Paul', 'George', 'Ringo'

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

1//ES6
2let uniqueArray = [...new Set(arrayWithDuplicates)];
3
4//Alternative
5function removeArrayDuplicates(arrayWithDuplicates) {
6    let seen = {};
7    let uniqueArray = [];
8    let len = arrayWithDuplicates.length;
9    let j = 0;
10    for(let i = 0; i < len; i++) {
11         let item = arrayWithDuplicates[i];
12         if(seen[item] !== 1) {
13               seen[item] = 1;
14               uniqueArray[j++] = item;
15         }
16    }
17    return uniqueArray;
18}