how to filter out duplicates in array javascript code example

Example 1: js delete duplicates from array

const names = ['John', 'Paul', 'George', 'Ringo', 'John'];

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

Example 2: javascript remove duplicate in arrays

// 1. filter()
function removeDuplicates(array) {
  return array.filter((a, b) => array.indexOf(a) === b)
};
// 2. forEach()
function removeDuplicates(array) {
  let x = {};
  array.forEach(function(i) {
    if(!x[i]) {
      x[i] = true
    }
  })
  return Object.keys(x)
};
// 3. Set
function removeDuplicates(array) {
  array.splice(0, array.length, ...(new Set(array)))
};
// 4. map()
function removeDuplicates(array) {
  let a = []
  array.map(x => 
    if(!a.includes(x) {
      a.push(x)
    })
  return a
};
/THIS SITE/ "https://dev.to/mshin1995/back-to-basics-removing-duplicates-from-an-array-55he#comments"

Example 3: use set to remove duplicates in javascript

const names = ['John', 'Paul', 'George', 'Ringo', 'John'];

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

Example 4: javascript remove duplicates from array

function toUniqueArray(a){
    var newArr = [];
    for (var i = 0; i < a.length; i++) {
        if (newArr.indexOf(a[i]) === -1) {
            newArr.push(a[i]);
        }
    }
  return newArr;
}
var colors = ["red","red","green","green","green"];
var colorsUnique=toUniqueArray(colors); // ["red","green"]

Example 5: use set to remove duplicates in javascript

const names = ['John', 'Paul', 'George', 'Ringo', 'John'];

let x = (names) => names.filter((v,i) => names.indexOf(v) === i)
x(names); // 'John', 'Paul', 'George', 'Ringo'

Example 6: javascript remove duplicates from array

let chars = ['A', 'B', 'A', 'C', 'B'];
let uniqueChars = [...new Set(chars)];

console.log(uniqueChars);
Code language: JavaScript (javascript)