how delete duplicate from array code example
Example 1: js delete duplicates from array
const names = ['John', 'Paul', 'George', 'Ringo', 'John'];
let unique = [...new Set(names)];
console.log(unique);
Example 2: remove duplicates from array javascript
function onlyUnique(value, index, self) {
return self.indexOf(value) === index;
}
var a = ['a', 1, 'a', 2, '1'];
var unique = a.filter(onlyUnique);
console.log(unique);
Example 3: remove duplicates array javascript
function uniqByKeepFirst(a, key) {
let seen = new Set();
return a.filter(item => {
let k = key(item);
return seen.has(k) ? false : seen.add(k);
});
}
function uniqByKeepLast(a, key) {
return [
...new Map(
a.map(x => [key(x), x])
).values()
]
}
data = [
{a:1, u:1},
{a:2, u:2},
{a:3, u:3},
{a:4, u:1},
{a:5, u:2},
{a:6, u:3},
];
console.log(uniqByKeepFirst(data, it => it.u))
console.log(uniqByKeepLast(data, it => it.u))