invertBy
INFO
This function is only available in es-toolkit/compat for compatibility reasons. It either has alternative native JavaScript APIs or isn’t fully optimized yet.
When imported from es-toolkit/compat, it behaves exactly like lodash and provides the same functionalities, as detailed here.
Creates a new object that reverses the keys and values of the given object, similar to the invert function.
The iteratee function specifies how the values are reversed into keys. If no iteratee function is provided, the values are used as keys as-is.
The values of the new object are arrays of keys that correspond to the value returned by the iteratee function.
Signature
typescript
function invertBy<K extends PropertyKey, V>(object: Record<K, V>, iteratee?: (value: V) => string): Record<string, K[]>;Parameters
object(Record<K, V>): The object to iterate over.iteratee((value: V) => string): A function applied to each value to generate a key. If not provided, defaults to a function that converts the value to a string.
Returns
(Record<string, K[]>): An object where each key is the result of the iteratee, and the corresponding value is an array of property names from the input object that produced that value.
Examples
typescript
import { invertBy } from 'es-toolkit/compat';
const obj = { a: 1, b: 2, c: 1 };
const result = invertBy(obj);
console.log(result); // => { '1': ['a', 'c'], '2': ['b'] }
const customResult = invertBy(obj, value => `group${value}`);
console.log(customResult); // => { 'group1': ['a', 'c'], 'group2': ['b'] }