main.js (1695B)
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 isString = require( './../../is-string' ).isPrimitive; 24 25 26 // VARIABLES // 27 28 // Character codes: 29 var ZERO = 48; 30 var NINE = 57; 31 var A = 65; 32 var F = 70; 33 var a = 97; 34 var f = 102; 35 36 37 // MAIN // 38 39 /** 40 * Tests whether a string contains only hexadecimal digits. 41 * 42 * @param {*} x - value to test 43 * @returns {boolean} boolean indicating if a string contains only hexadecimal digits 44 * 45 * @example 46 * var out = isHexString( '0123456789abcdefABCDEF' ); 47 * // returns true 48 * 49 * @example 50 * var out = isHexString( '0xffffff' ); 51 * // returns false 52 * 53 * @example 54 * var out = isHexString( '' ); 55 * // returns false 56 * 57 * @example 58 * var out = isHexString( 123 ); 59 * // returns false 60 */ 61 function isHexString( x ) { 62 var len; 63 var ch; 64 var i; 65 if ( !isString( x ) ) { 66 return false; 67 } 68 len = x.length; 69 if ( !len ) { 70 return false; 71 } 72 for ( i = 0; i < len; i++ ) { 73 ch = x.charCodeAt( i ); 74 if ( 75 ch < ZERO || 76 ( ch > NINE && ch < A ) || 77 ( ch > F && ch < a ) || 78 ch > f 79 ) { 80 return false; 81 } 82 } 83 return true; 84 } 85 86 87 // EXPORTS // 88 89 module.exports = isHexString;