how to use the findkey function from the underscore library in javascript

The _.findKey() function in Underscore is used to return the first key at which a given predicate function returns true.

Here's an example of how to use the _.findKey() function:

index.tsx
const _ = require('underscore');

const users = {
  'user1': { 'age': 25, 'active': true },
  'user2': { 'age': 30, 'active': false },
  'user3': { 'age': 35, 'active': true }
};

const activeUser = _.findKey(users, function(user) {
  return user.active;
});

console.log(activeUser); // Output: user1
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In this example, we have an object called users with multiple key-value pairs. We are using the _.findKey() function to return the first key where the predicate function (which checks if the user is active) returns true.

Note that the predicate function takes a parameter user, which represents the current value of the object as it traverses through the keys.