feat: new function - groupBy

README.md

@@ -96,6 +96,7 @@ pnpm add @utopia-utils/dom
 * pipe: 函数组合, 从左到右执行。[source](https://github.com/GreatAuk/utopia-utils/blob/main/packages/core/src/pipe.ts)
 * onlyResolvesLast: 解决竞态问题，只保留最后一次调用的结果。[source](https://github.com/GreatAuk/utopia-utils/blob/main/packages/core/src/onlyResolvesLast.ts)
 * parseQuery: 解析 url query。[source](https://github.com/GreatAuk/utopia-utils/blob/main/packages/core/src/parseQuery.ts)
+* groupBy: 数组根据指定的 key 分组。[source](https://github.com/GreatAuk/utopia-utils/blob/main/packages/core/src/groupBy.ts)
 ### 类型判断
 
 ```bash

packages/core/src/groupBy.test.ts

@@ -0,0 +1,27 @@
+import { groupBy } from './groupBy'
+
+describe('groupBy', () => {
+  it('should group by a string', () => {
+    const array = [
+      { name: 'John', age: 20 },
+      { name: 'Jane', age: 25 },
+      { name: 'Jack', age: 20 },
+    ]
+
+    const result = groupBy(array, item => `${item.age}`)
+    expect(result).toEqual({
+      20: [
+        { name: 'John', age: 20 },
+        { name: 'Jack', age: 20 },
+      ],
+      25: [{ name: 'Jane', age: 25 }],
+    })
+
+    const arr2 = [4.2, 6.3, 6.5]
+    const result2 = groupBy(arr2, v => `${Math.floor(v)}`)
+    expect(result2).toEqual({
+      4: [4.2],
+      6: [6.3, 6.5],
+    })
+  })
+})

packages/core/src/groupBy.ts

@@ -0,0 +1,25 @@
+/**
+ * group an array by a string
+ * @param {T[]} array - The array to iterate over.
+ * @param iteratee - (item: T) => string
+ * @returns {Record<string, T[]>} Returns the composed aggregate object.
+ * @example
+ * ```
+    groupBy([4.2, 6.3, 6.5], v => `${Math.floor(v)}`)
+    // { '4': [ 4.2 ], '6': [ 6.3, 6.5 ] }
+
+    groupBy([{ name: 'John', age: 20 }, { name: 'Jane', age: 25 }], item => `${item.age}`)
+    // { '20': [ { name: 'John', age: 20 } ], '25': [ { name: 'Jane', age: 25 } ] }
+ * ```
+ */
+export function groupBy<T>(array: T[], iteratee: (item: T) => string): Record<string, T[]> {
+  return array.reduce<Record<string, T[]>>((acc, item) => {
+    const key = iteratee(item)
+    if (acc[key])
+      acc[key].push(item)
+    else
+      acc[key] = [item]
+
+    return acc
+  }, {})
+}

packages/core/src/index.ts

@@ -16,6 +16,7 @@ export * from './escapeStringRegexp'
 export * from './getByPath'
 export * from './getFileName'
 export * from './getQueryParams'
+export * from './groupBy'
 export * from './intersection'
 export * from './math'
 export * from './memoize'