findKey source npm

_.findKey(object, [predicate=_.identity])

This method is like _.find except that it returns the key of the first element predicate returns truthy for instead of the element itself.

Arguments

  1. object (Object)

    The object to search.

  2. [predicate=_.identity] (Function|Object|string)

    The function invoked per iteration.

Returns (string|undefined)

Returns the key of the matched element, else undefined.

Example

var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findKey(users, function(o) { return o.age < 40; });
// => 'barney' (iteration order is not guaranteed)

// using the `_.matches` callback shorthand
_.findKey(users, { 'age': 1, 'active': true });
// => 'pebbles'

// using the `_.matchesProperty` callback shorthand
_.findKey(users, ['active', false]);
// => 'fred'

// using the `_.property` callback shorthand
_.findKey(users, 'active');
// => 'barney'