Function countBy

countBy<T, TId extends string | number | symbol>(
list: readonly T[],
identity: (item: T) => TId,
): Record<TId, number>
计数，根据生成的key值来统计
Type Parameters
- T
- TId extends string | number | symbol
Parameters
- list: readonly T[]
- identity: (item: T) => TId
Returns Record<TId, number>
- Defined in src/modules/array.ts:225