if_then.js (1748B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MODULES // 22 23 var isFunction = require( '@stdlib/assert/is-function' ); 24 25 26 // MAIN // 27 28 /** 29 * If a condition is truthy, invokes `x`; otherwise, invokes `y`. 30 * 31 * @param {boolean} bool - condition 32 * @param {Function} x - function to invoke if a condition is truthy 33 * @param {Function} y - function to invoke if a condition is falsy 34 * @throws {TypeError} second argument must be a function 35 * @throws {TypeError} third argument must be a function 36 * @returns {*} return value of either `x` or `y` 37 * 38 * @example 39 * var randu = require( '@stdlib/random/base/randu' ); 40 * 41 * function x() { 42 * return randu() * 100.0; 43 * } 44 * 45 * function y() { 46 * return -1.0 * randu() * 100.0; 47 * } 48 * 49 * var z = ifthen( randu() > 0.5, x, y ); 50 * // returns <number> 51 */ 52 function ifthen( bool, x, y ) { 53 if ( !isFunction( x ) ) { 54 throw new TypeError( 'invalid argument. Second argument must be a function. Value: `'+x+'`.' ); 55 } 56 if ( !isFunction( y ) ) { 57 throw new TypeError( 'invalid argument. Third argument must be a function. Value: `'+y+'`.' ); 58 } 59 if ( bool ) { 60 return x(); 61 } 62 return y(); 63 } 64 65 66 // EXPORTS // 67 68 module.exports = ifthen;