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Lodash _.findKey

Overview

lodash is a popular JavaScript utility library that offers a wide range of helpful methods to make working with collections, objects, and functions in JavaScript easier and more efficient. One of the many useful methods offered by lodash is the _.findKey method.

The _.findKey method is used to iterate over an object and return the first key that matches a provided predicate function. The function takes two arguments: the value and key of each property in the object being iterated over.

Here’s an example of how to use _.findKey:

const users = {
  'user1': { 'name': 'John', 'age': 22 },
  'user2': { 'name': 'Jane', 'age': 27 },
  'user3': { 'name': 'Bob', 'age': 31 },
  'user4': { 'name': 'Alice', 'age': 25 }
};

const result1 = _.findKey(users, (user) => user.age > 26);
const result2 = _.findKey(users, (user) => user.name === 'Bob');

console.log(result1); // "user2"
console.log(result2); // "user3"

In the first example, _.findKey returns the first key that has a value with an age property greater than 26 (which is "user2"). In the second example, it returns the first key that has a value with a name property equal to "Bob" (which is "user3").

If no matching key is found, _.findKey returns undefined. The method is also chainable, meaning it can be used with other lodash methods.

Overall, the _.findKey method is a convenient way to quickly find the first key in an object that matches a specific criterion, saving developers time and making their code more readable.