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55 lines
1.8 KiB
JavaScript

var baseForOwn = require('../internal/baseForOwn'),
createFindKey = require('../internal/createFindKey');
/**
* This method is like `_.find` except that it returns the key of the first
* element `predicate` returns truthy for instead of the element itself.
*
* If a property name is provided for `predicate` the created `_.property`
* style callback returns the property value of the given element.
*
* If a value is also provided for `thisArg` the created `_.matchesProperty`
* style callback returns `true` for elements that have a matching property
* value, else `false`.
*
* If an object is provided for `predicate` the created `_.matches` style
* callback returns `true` for elements that have the properties of the given
* object, else `false`.
*
* @static
* @memberOf _
* @category Object
* @param {Object} object The object to search.
* @param {Function|Object|string} [predicate=_.identity] The function invoked
* per iteration.
* @param {*} [thisArg] The `this` binding of `predicate`.
* @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(chr) {
* return chr.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'
*/
var findKey = createFindKey(baseForOwn);
module.exports = findKey;