Array/Since 1.38.0

groupBy

Groups array elements into an object using the value of a specified object property as the group key.

groupBy(array, key):Record<string, T[]>

Parameters

arrayT[]required

The array of objects whose elements should be grouped.

keyKrequired

The property key whose value is used to determine the group for each element.

Returns

Record<string, T[]>

An object where each property represents a group and contains the array elements belonging to that group.

Examples

Basic usage

Group objects by the value of the specified property.

TypeScript

import { groupBy } from "@cyref/js";

const users = [
  { name: "Amir", role: "developer" },
  { name: "Sara", role: "designer" },
  { name: "Reza", role: "developer" },
];

const result = groupBy(users, "role");

console.log(result);
// {
//   developer: [
//     { name: "Amir", role: "developer" },
//     { name: "Reza", role: "developer" },
//   ],
//   designer: [
//     { name: "Sara", role: "designer" },
//   ],
// }

Group by category

The key can be any property key available on the object type.

TypeScript

import { groupBy } from "@cyref/js";

const products = [
  { name: "Laptop", category: "electronics" },
  { name: "Phone", category: "electronics" },
  { name: "T-Shirt", category: "clothing" },
];

const result = groupBy(products, "category");

console.log(result);
// {
//   electronics: [
//     { name: "Laptop", category: "electronics" },
//     { name: "Phone", category: "electronics" },
//   ],
//   clothing: [
//     { name: "T-Shirt", category: "clothing" },
//   ],
// }

Single-item groups

Values that occur only once create groups containing a single element.

TypeScript

import { groupBy } from "@cyref/js";

const items = [
  { id: 1, type: "a" },
  { id: 2, type: "b" },
  { id: 3, type: "a" },
];

const result = groupBy(items, "type");

console.log(result);
// {
//   a: [
//     { id: 1, type: "a" },
//     { id: 3, type: "a" },
//   ],
//   b: [
//     { id: 2, type: "b" },
//   ],
// }

Empty array

An empty input array produces an empty object.

TypeScript

import { groupBy } from "@cyref/js";

const result = groupBy([], "type");

console.log(result);
// {}

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