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55 lines
1.8 KiB
JavaScript
55 lines
1.8 KiB
JavaScript
9 years ago
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var baseForOwn = require('../internal/baseForOwn'),
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createFindKey = require('../internal/createFindKey');
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/**
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* This method is like `_.find` except that it returns the key of the first
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* element `predicate` returns truthy for instead of the element itself.
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*
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* If a property name is provided for `predicate` the created `_.property`
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* style callback returns the property value of the given element.
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*
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* If a value is also provided for `thisArg` the created `_.matchesProperty`
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* style callback returns `true` for elements that have a matching property
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* value, else `false`.
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*
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* If an object is provided for `predicate` the created `_.matches` style
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* callback returns `true` for elements that have the properties of the given
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* object, else `false`.
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*
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* @static
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* @memberOf _
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* @category Object
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* @param {Object} object The object to search.
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* @param {Function|Object|string} [predicate=_.identity] The function invoked
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* per iteration.
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* @param {*} [thisArg] The `this` binding of `predicate`.
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* @returns {string|undefined} Returns the key of the matched element, else `undefined`.
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* @example
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*
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* var users = {
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* 'barney': { 'age': 36, 'active': true },
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* 'fred': { 'age': 40, 'active': false },
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* 'pebbles': { 'age': 1, 'active': true }
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* };
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*
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* _.findKey(users, function(chr) {
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* return chr.age < 40;
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* });
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* // => 'barney' (iteration order is not guaranteed)
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*
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* // using the `_.matches` callback shorthand
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* _.findKey(users, { 'age': 1, 'active': true });
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* // => 'pebbles'
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*
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* // using the `_.matchesProperty` callback shorthand
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* _.findKey(users, 'active', false);
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* // => 'fred'
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*
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* // using the `_.property` callback shorthand
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* _.findKey(users, 'active');
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* // => 'barney'
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*/
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var findKey = createFindKey(baseForOwn);
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module.exports = findKey;
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