main.js (1581B)
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 32 33 // MAIN // 34 35 /** 36 * Tests whether a string contains only numeric digits. 37 * 38 * @param {*} x - value to test 39 * @returns {boolean} boolean indicating if a string contains only numeric digits 40 * 41 * @example 42 * var out = isDigitString( '0123456789' ); 43 * // returns true 44 * 45 * @example 46 * var out = isDigitString( '0xffffff' ); 47 * // returns false 48 * 49 * @example 50 * var out = isDigitString( '' ); 51 * // returns false 52 * 53 * @example 54 * var out = isDigitString( 123 ); 55 * // returns false 56 */ 57 function isDigitString( x ) { 58 var len; 59 var ch; 60 var i; 61 if ( !isString( x ) ) { 62 return false; 63 } 64 len = x.length; 65 if ( len === 0 ) { 66 return false; 67 } 68 for ( i = 0; i < len; i++ ) { 69 ch = x.charCodeAt( i ); 70 if ( ch < ZERO || ch > NINE ) { 71 return false; 72 } 73 } 74 return true; 75 } 76 77 78 // EXPORTS // 79 80 module.exports = isDigitString;