主题
findIndex
js
_.findIndex(array, [predicate=_.identity], [fromIndex=0])
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索引,而不是元素本身。
¥This method is like _.find
except that it returns the index of the first element predicate
returns truthy for instead of the element itself.
新增于
¥Since
1.1.0
参数
¥Arguments
array
(数组):要检查的数组。¥
array
(Array): The array to inspect.[predicate=_.identity]
(函数):每次迭代调用的函数。¥
[predicate=_.identity]
(Function): The function invoked per iteration.[fromIndex=0]
(数值):要从中搜索的索引。¥
[fromIndex=0]
(number): The index to search from.
返回
¥Returns
(数值):返回找到的元素的索引,否则为 -1
。
¥(number): Returns the index of the found element, else -1
.
示例
¥Example
js
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': true }
];
_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0
// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1
// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0
// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2