To get the intersection of two Sets in JavaScript, combine the filter() and has() array methods:
const set1 = new Set([1, 2, 3, 4, 5]);
const set2 = new Set([4, 5, 6, 7, 8]);
const intersection = new Set([...set1].filter(x => set2.has(x)));
console.log(intersection); // Set {4, 5}The Array filter() method tests each element in an array against a condition specified by a callback function and creates a new array filled with elements that pass the test. It doesn’t modify the original array.
const arr = [1, 2, 3, 4];
const filtered = arr.filter((num) => num > 2);
console.log(filtered); // [ 3, 4 ]The spread syntax (...) converts the Set to an array:
const set1 = new Set([1, 2, 3, 4, 5]);
const arrayFromSet = [...set1];
console.log(arrayFromSet); // [1, 2, 3, 4, 5]We can also do this with the Array from() method, which converts Sets and other iterables into arrays:
const set1 = new Set([1, 2, 3, 4, 5]);
const arrayFromSet = Array.from(set1);
console.log(arrayFromSet); // [1, 2, 3, 4, 5]And the Set has() method tells us whether or not the Set contains a particular element.
const set = new Set(['coding', 'beauty', 'dev']);
const hasElegance = set.has('elegance');
const hasBeauty = set.has('beauty');
console.log(hasElegance); // false
console.log(hasBeauty); // trueGet intersection of two sets with Array forEach() method
Alternatively, we can use the Array forEach() method to get the intersection of two Sets in JavaScript.
const set1 = new Set([1, 2, 3, 4, 5]);
const set2 = new Set([4, 5, 6, 7, 8]);
const intersection = new Set();
set1.forEach(value => {
if (set2.has(value)) {
intersection.add(value);
}
});
console.log(intersection); // Set {4, 5}The Set forEach loops through an array and calls a specified function on each element.
const fruits = new Set(['apple', 'orange', 'banana']);
fruits.forEach((fruit) => {
console.log(fruit.toUpperCase());
});
// Output 👇
// APPLE
// ORANGE
// BANANAThe Set add() method adds a new element to a Set:
const set = new Set([1, 2, 3]);
console.log(set); // Set(3) { 1, 2, 3 }
set.add(10);
console.log(set); // Set(4) { 1, 2, 3, 10 }Get intersection of two Sets with for..of loop
Anywhere you see the forEach(), you can use the for..of loop in its place:
const set1 = new Set([1, 2, 3, 4, 5]);
const set2 = new Set([4, 5, 6, 7, 8]);
const intersection = new Set();
for (const value of set1) {
if (set2.has(value)) {
intersection.add(value);
}
}
console.log(intersection); // Set {4, 5}Get intersection of two Sets with reduce() method
You can also use the reduce() method to get the intersection of two Set objects in JavaScript:
const set1 = new Set([1, 2, 3, 4, 5]);
const set2 = new Set([4, 5, 6, 7, 8]);
const intersection = [...set1].reduce((acc, value) => {
if (set2.has(value)) {
acc.add(value);
}
return acc;
}, new Set());
console.log(intersection); // Set {4, 5}The reduce() method calls a function on each element of an array to accumulate a resulting value:
const nums = [1, 2, 3, 4, 5];
const sum = nums.reduce((acc, num) => acc + num, 0);
const product = nums.reduce((acc, num) => acc * num, 1);
console.log(sum); // 15
console.log(product); // 120Every Crazy Thing JavaScript Does
A captivating guide to the subtle caveats and lesser-known parts of JavaScript.
