main.js (1611B)
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 getPrototypeOf = require( '@stdlib/utils/get-prototype-of' ); 24 var nativeClass = require( '@stdlib/utils/native-class' ); 25 26 27 // MAIN // 28 29 /** 30 * Tests if a value is an `Error` object. 31 * 32 * @param {*} value - value to test 33 * @returns {boolean} boolean indicating whether a value is an `Error` object 34 * 35 * @example 36 * var bool = isError( new Error( 'beep' ) ); 37 * // returns true 38 * 39 * @example 40 * var bool = isError( {} ); 41 * // returns false 42 */ 43 function isError( value ) { 44 if ( typeof value !== 'object' || value === null ) { 45 return false; 46 } 47 // Check for `Error` objects from the same realm (same Node.js `vm` or same `Window` object)... 48 if ( value instanceof Error ) { 49 return true; 50 } 51 // Walk the prototype tree until we find an object having the desired native class... 52 while ( value ) { 53 if ( nativeClass( value ) === '[object Error]' ) { 54 return true; 55 } 56 value = getPrototypeOf( value ); 57 } 58 return false; 59 } 60 61 62 // EXPORTS // 63 64 module.exports = isError;