First duplicate value occurence using Map
const num = [1, 2, 3, 4, 2, 3, 4, 6, 8];
let map = new Map();
let output = num.map((item) => {
if (map.has(item)) {
return item;
}
map.set(item);
});
//output - [undefined, undefined, undefined, undefined, 2, 3, 4, undefined, undefined]
console.log(output.find((i) => i));
First duplicate value occurence using Filter
const num = [1, 2, 3, 4, 2, 3, 4, 6, 8];
let map = new Map();
let output = num.filter((item) => {
if (map.has(item)) {
return item;
}
map.set(item);
});
//output - [2, 3, 4]
//This also fetches you all duplicates in the array- 2 3 4
console.log(output[0]);
First duplicate value occurence using Find
const num = [1, 2, 3, 4, 2, 3, 4, 6, 8];
let map = new Map();
let output = num.find((item) => {
if (map.has(item)) {
return item;
}
map.set(item);
});
//output - 2
//This fetches you 2
console.log(output);
First duplicate value occurence using Every
const num = [1, 2, 3, 4, 2, 3, 4, 6, 8];
let map = new Map();
let final;
let output = num.every((item) => {
if (map.has(item)) {
final = item;
return false;
}
map.set(item);
return true;
});
console.log(final);
First duplicate value occurence using some
const num = [1, 2, 3, 4, 2, 3, 4, 6, 8];
let map = new Map();
let final;
let output = num.some((item) => {
if (map.has(item)) {
final = item;
return true;
}
map.set(item);
});
// //output - 2
console.log(final);