async.js (1723B)
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 fs = require( 'fs' ); 24 25 26 // FUNCTIONS // 27 28 var fcn; 29 if ( typeof fs.access === 'function' ) { 30 fcn = fs.access; 31 } else { 32 fcn = fs.stat; 33 } 34 35 36 // MAIN // 37 38 /** 39 * Tests whether a path exists on the filesystem. 40 * 41 * @param {(string|Buffer)} path - path to test 42 * @param {Function} clbk - callback to invoke after testing path existence 43 * 44 * @example 45 * exists( __dirname, done ); 46 * 47 * function done( error, bool ) { 48 * if ( error ) { 49 * console.error( error ); 50 * } 51 * if ( bool ) { 52 * console.log( '...path exists.' ); 53 * } else { 54 * console.log( '...path does not exist.' ); 55 * } 56 * } 57 */ 58 function exists( path, clbk ) { 59 fcn( path, done ); 60 61 /** 62 * Callback invoked upon performing a filesystem call. 63 * 64 * @private 65 * @param {(Error|null)} error - error object 66 * @returns {void} 67 */ 68 function done( error ) { 69 if ( clbk.length === 2 ) { 70 if ( error ) { 71 return clbk( error, false ); 72 } 73 return clbk( null, true ); 74 } 75 if ( error ) { 76 return clbk( false ); 77 } 78 return clbk( true ); 79 } 80 } 81 82 83 // EXPORTS // 84 85 module.exports = exists;