This content originally appeared on Bram.us and was authored by Bramus!
An ECMAScript Proposal that recently made it to Stage-3 is array grouping. The proposal brings us the array.groupBy() and array.groupByToMap() methods to easily group arrays.
~
💁♂️ Stage-3?
The Technical Committee which is concerned with the standardization of ECMAScript (i.e. TC39) has a 5 stage process in place, ranging from stage-0 to stage-4, by which it develops a new language feature.
Stage-3 is the Candidate Stage where the feature is considered complete and only critical changes will happen based on implementation experience. If all goes well the proposal will advance to Stage 4 without any changes, after which it will to become part of the ECMAScript Specification.
~
The Proposal
The proposal offers two methods:
Two methods are offered,
groupByandgroupByToMap. The first returns a null-prototype object, which allows ergonomic destructuring and prevents accidental collisions with global Object properties. The second returns a regular Map instance, which allows grouping on complex key types.
With these methods you’ll be able to stop using array.reduce() — a method not everyone likes — to achieve grouping.
~
Examples
Take this array as input:
const array = [1, 2, 3, 4, 5];>With array.groupBy you can create groups using arbitrary keys. The result is an regular JavaScript object:
array.groupBy((num, index, array) => {
return num % 2 === 0 ? 'even': 'odd';
});
// => { odd: [1, 3, 5], even: [2, 4] }>The array.groupByToMap method does the same, but it allows you to use complex types (i.e. objects) as keys. The result is a Map:
const odd = { odd: true };
const even = { even: true };
array.groupByToMap((num, index, array) => {
return num % 2 === 0 ? even: odd;
});
// => Map { {odd: true}: [1, 3, 5], {even: true}: [2, 4] }>~
Engine Support
The methods are currently not supported in any JavaScript Engine. A polyfill is available in the core-js library.
~
🔥 Like what you see? Want to stay in the loop? Here's how:
This content originally appeared on Bram.us and was authored by Bramus!
Bramus! | Sciencx (2021-12-21T22:55:59+00:00) ESNext: Sort arrays using array.groupBy() and array.groupByToMap(). Retrieved from https://www.scien.cx/2021/12/21/esnext-sort-arrays-using-array-groupby-and-array-groupbytomap/
Please log in to upload a file.
There are no updates yet.
Click the Upload button above to add an update.