Use JavaScript's New Set Composition Methods Without Polyfillsby@thangaganapathy

# Use JavaScript's New Set Composition Methods Without Polyfills

April 22nd, 2024

There is a proposal to add methods like union and intersection to JavaScript's built-in Set class. It is currently at stage 3, but some browsers like Chrome already support it. Currently, you can safely use these methods by using polyfills. Let us explain each method by examples of how to use these functions.

Welcome,

There is a proposal to add methods like union and intersection to JavaScript's built-in Set class.

It is currently at stage 3, but some browsers like Chrome already support it.

As you can see, the currently supported runtimes are very limited.

## Polyfills

Currently, you can safely use these methods by using polyfills.

## Set Composition Methods

These methods include:

• Set.prototype.intersection(other)
• Set.prototype.union(other)
• Set.prototype.difference(other)
• Set.prototype.symmetricDifference(other)
• Set.prototype.isSubsetOf(other)
• Set.prototype.isSupersetOf(other)
• Set.prototype.isDisjointFrom(other)

## Using without Polyfills

You can use our std library functions to achieve the same.

Let us explain each method by examples of how to use these functions.

Set.prototype.intersection()

import { intersection } from '@opentf/std';

const odds = [1, 3, 5, 7, 9];
const squares = [1, 4, 9];

// Using native method
new Set(odds).intersection(new Set(squares)); //=> Set(2) { 1, 9 }

// Using std function
intersection([odds, squares]); //=> [ 1, 9 ]

Set.prototype.union()

import { union } from '@opentf/std';

const evens = [2, 4, 6, 8];
const squares = [1, 4, 9];

// Using native method
new Set(evens).union(new Set(squares)); //=> Set(6) { 2, 4, 6, 8, 1, 9 }

// Using std function
union([evens, squares]); //=> [ 2, 4, 6, 8, 1, 9 ]

Set.prototype.difference()

import { diff } from '@opentf/std';

const odds = [1, 3, 5, 7, 9];
const squares = [1, 4, 9];

// Using native method
new Set(odds).difference(new Set(squares)); //=> Set(3) { 3, 5, 7 }

// Using std function
diff([odds, squares]); //=> [ 3, 5, 7 ]

Set.prototype.symmetricDifference()

import { symDiff } from '@opentf/std';

const evens = [2, 4, 6, 8];
const squares = [1, 4, 9];

// Using native method
new Set(evens).symmetricDifference(new Set(squares));
//=> Set(5) {2, 6, 8, 1, 9}

// Using std function
symDiff([evens, squares]); //=> [ 2, 6, 8, 1, 9 ]

Set.prototype.isSubsetOf()

import { isSubsetOf } from '@opentf/std';

const fours = [4, 8, 12, 16];
const evens = [2, 4, 6, 8, 10, 12, 14, 16, 18];

// Using native method
new Set(fours).isSubsetOf(new Set(evens)); //=> true

// Using std function
isSubsetOf(fours, evens); //=> true

Set.prototype.isSupersetOf()

import { isSupersetOf } from '@opentf/std';

const evens = [2, 4, 6, 8, 10, 12, 14, 16, 18];
const fours = [4, 8, 12, 16];

// Using native method
new Set(evens).isSupersetOf(new Set(fours)); //=> true

// Using std function
isSupersetOf(evens, fours); //=> true

Set.prototype.isDisjointFrom()

import { isDisjointFrom } from '@opentf/std';

const primes = [2, 3, 5, 7, 11, 13, 17, 19];
const squares = [1, 4, 9, 16];

// Using native method
new Set(primes).isDisjointFrom(new Set(squares)); //=> true

// Using std function
isDisjointFrom(primes, squares); //=> true

## Bonus

The subset relationship can be determined by passing the Boolean value to the proper param. Learn more about it on our website.

## Conclusion

By using our library functions, you can compose sets like you would with mathematical operations.

Here are some of the benefits from using our library:

• Works across runtimes, e.g. Browsers, Node.js, Bun, Deno, etc.

• Consistent & Concise function names

• TypeScript Support

• Works with both CJS & ESM

• Supports some Older Browsers & Node.js >= 16

And finally, you can avoid polyfills in your codebase.

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Happy coding! 🚀