Yang Guo | 4fd355c | 2019-09-19 08:59:03 | [diff] [blame] | 1 | /** Error message constants. */ |
| 2 | var FUNC_ERROR_TEXT = 'Expected a function'; |
| 3 | |
| 4 | /** |
| 5 | * Creates a function that negates the result of the predicate `func`. The |
| 6 | * `func` predicate is invoked with the `this` binding and arguments of the |
| 7 | * created function. |
| 8 | * |
| 9 | * @static |
| 10 | * @memberOf _ |
| 11 | * @since 3.0.0 |
| 12 | * @category Function |
| 13 | * @param {Function} predicate The predicate to negate. |
| 14 | * @returns {Function} Returns the new negated function. |
| 15 | * @example |
| 16 | * |
| 17 | * function isEven(n) { |
| 18 | * return n % 2 == 0; |
| 19 | * } |
| 20 | * |
| 21 | * _.filter([1, 2, 3, 4, 5, 6], _.negate(isEven)); |
| 22 | * // => [1, 3, 5] |
| 23 | */ |
| 24 | function negate(predicate) { |
| 25 | if (typeof predicate != 'function') { |
| 26 | throw new TypeError(FUNC_ERROR_TEXT); |
| 27 | } |
| 28 | return function() { |
| 29 | var args = arguments; |
| 30 | switch (args.length) { |
| 31 | case 0: return !predicate.call(this); |
| 32 | case 1: return !predicate.call(this, args[0]); |
| 33 | case 2: return !predicate.call(this, args[0], args[1]); |
| 34 | case 3: return !predicate.call(this, args[0], args[1], args[2]); |
| 35 | } |
| 36 | return !predicate.apply(this, args); |
| 37 | }; |
| 38 | } |
| 39 | |
| 40 | module.exports = negate; |