main.js (1935B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2021 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( '@stdlib/assert/is-string' ).isPrimitive; 24 var format = require( './../../format' ); 25 26 27 // MAIN // 28 29 /** 30 * Returns the part of a string before the last occurrence of a specified substring. 31 * 32 * @param {string} str - input string 33 * @param {string} search - search value 34 * @throws {TypeError} first argument must be a string 35 * @throws {TypeError} second argument must be a string 36 * @returns {string} substring 37 * 38 * @example 39 * var out = substringBeforeLast( 'abcba', 'b' ); 40 * // returns 'abc' 41 * 42 * @example 43 * var out = substringBeforeLast( 'Hello World, my friend!', ' ' ); 44 * // returns 'Hello World, my' 45 * 46 * @example 47 * var out = substringBeforeLast( 'abcba', ' ' ); 48 * // returns 'abcba' 49 * 50 * @example 51 * var out = substringBeforeLast( 'abcba', '' ); 52 * // returns 'abcba' 53 */ 54 function substringBeforeLast( str, search ) { 55 var idx; 56 if ( !isString( str ) ) { 57 throw new TypeError( format( 'invalid argument. First argument must be a string. Value: `%s`.', str ) ); 58 } 59 if ( !isString( search ) ) { 60 throw new TypeError( format( 'invalid argument. Second argument must be a string. Value: `%s`.', search ) ); 61 } 62 idx = str.lastIndexOf( search ); 63 if ( idx === -1 ) { 64 return str; 65 } 66 return str.substring( 0, idx ); 67 } 68 69 70 // EXPORTS // 71 72 module.exports = substringBeforeLast;