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findKey

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

此方法与 _.find 类似,不同之处在于它返回 predicate 返回真值的第一个元素的键,而不是元素本身。

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

新增于

¥Since

1.1.0

参数

¥Arguments

  1. object (对象):要反转的对象。

    ¥object (Object): The object to inspect.

  2. [predicate=_.identity] (函数):每次迭代调用的函数。

    ¥[predicate=_.identity] (Function): The function invoked per iteration.

返回

¥Returns

(*):返回匹配元素的键,否则为 undefined

¥()*: Returns the key of the matched element, else undefined.

示例

¥Example

js
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)

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

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

// The `_.property` iteratee shorthand.
_.findKey(users, 'active');
// => 'barney'

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