blob: f7e28a1d423a8e25e8cad30a78ac64837cef4db2 [file] [log] [blame]
var baseCallback = require('../internal/baseCallback'),
baseWhile = require('../internal/baseWhile');
/**
* Creates a slice of `array` with elements taken from the beginning. Elements
* are taken until `predicate` returns falsey. The predicate is bound to
* `thisArg` and invoked with three arguments: (value, index, array).
*
* 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 Array
* @param {Array} array The array to query.
* @param {Function|Object|string} [predicate=_.identity] The function invoked
* per iteration.
* @param {*} [thisArg] The `this` binding of `predicate`.
* @returns {Array} Returns the slice of `array`.
* @example
*
* _.takeWhile([1, 2, 3], function(n) {
* return n < 3;
* });
* // => [1, 2]
*
* var users = [
* { 'user': 'barney', 'active': false },
* { 'user': 'fred', 'active': false},
* { 'user': 'pebbles', 'active': true }
* ];
*
* // using the `_.matches` callback shorthand
* _.pluck(_.takeWhile(users, { 'user': 'barney', 'active': false }), 'user');
* // => ['barney']
*
* // using the `_.matchesProperty` callback shorthand
* _.pluck(_.takeWhile(users, 'active', false), 'user');
* // => ['barney', 'fred']
*
* // using the `_.property` callback shorthand
* _.pluck(_.takeWhile(users, 'active'), 'user');
* // => []
*/
function takeWhile(array, predicate, thisArg) {
return (array && array.length)
? baseWhile(array, baseCallback(predicate, thisArg, 3))
: [];
}
module.exports = takeWhile;