set.prototype.difference/README.md

An ESnext spec-compliant `Set.prototype.difference` shim/polyfill/replacement that works as far down as ES3

# set.prototype.difference <sup>[![Version Badge][npm-version-svg]][package-url]</sup>

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ES Proposal spec-compliant shim for Set.prototype.difference. Invoke its "shim" method to shim `Set.prototype.difference` if it is unavailable or noncompliant.

This package implements the [es-shim API](https://github.com/es-shims/api) interface. It works in an ES3-supported environment, and complies with the [proposed spec](https://github.com/tc39/proposal-set-methods). When shimmed, it uses [`es-set`](https://npmjs.com/es-set) to shim the `Set` implementation itself if needed.

Most common usage:
```js
var assert = require('assert');
var difference = require('set.prototype.difference');

var set1 = new Set([1, 2]);
var set2 = new Set([2, 3]);
var result = difference(set1, set2);

assert.deepEqual(result, new Set([1]));

difference.shim();

var shimmedResult = set1.difference(set2);
assert.deepEqual(shimmedResult, new Set([1]));
```

## Compatibility
node v22 and equivalent versions of Chrome have Set difference, but has a bug with set-like arguments with non-SMI integer sizes.

## Tests
Simply clone the repo, `npm install`, and run `npm test`

## Set Method Packages
 - [union](https://npmjs.com/set.prototype.union)
 - [intersection](https://npmjs.com/set.prototype.intersection)
 - [difference](https://npmjs.com/set.prototype.difference)
 - [symmetricDifference](https://npmjs.com/set.prototype.symmetricdifference)
 - [isSubsetOf](https://npmjs.com/set.prototype.issubsetof)
 - [isSupersetOf](https://npmjs.com/set.prototype.issupersetof)
 - [isDisjointFrom](https://npmjs.com/set.prototype.isdisjointfrom)

[package-url]: https://npmjs.com/package/set.prototype.difference
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[dev-deps-url]: https://david-dm.org/es-shims/Set.prototype.difference#info=devDependencies
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[testling-url]: https://ci.testling.com/es-shims/Set.prototype.difference
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