90 lines
2.4 KiB
JavaScript
90 lines
2.4 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
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var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
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var prevGraphemeClusterBreak = require( './../../prev-grapheme-cluster-break' );
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var format = require( './../../format' );
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// MAIN //
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/**
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* Removes the last character(s) of a string.
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*
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* @param {string} str - input string
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* @param {NonNegativeInteger} [n=1] - number of character to remove
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* @throws {TypeError} must provide a string primitive
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* @throws {TypeError} second argument must be a nonnegative integer
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* @returns {string} updated string
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*
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* @example
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* var out = removeLast( 'last man standing' );
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* // returns 'last man standin'
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*
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* @example
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* var out = removeLast( 'presidential election' );
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* // returns 'presidential electio'
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*
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* @example
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* var out = removeLast( 'javaScript' );
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* // returns 'javaScrip'
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*
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* @example
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* var out = removeLast( 'Hidden Treasures' );
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* // returns 'Hidden Treasure'
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*
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* @example
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* var out = removeLast( 'leader', 2 );
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* // returns 'lead'
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*/
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function removeLast( str, n ) {
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var i;
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if ( !isString( str ) ) {
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throw new TypeError( format( 'invalid argument. First argument must be a string. Value: `%s`.', str ) );
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}
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if ( str === '' ) {
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return '';
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}
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if ( arguments.length > 1 ) {
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if ( !isNonNegativeInteger( n ) ) {
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throw new TypeError( format( 'invalid argument. Second argument must be a nonnegative integer. Value: `%s`.', n ) );
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}
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if ( n === 0 ) {
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return str;
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}
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i = str.length - 1;
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while ( n > 0 ) {
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i = prevGraphemeClusterBreak( str, i );
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n -= 1;
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}
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return str.substring( 0, i + 1 );
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}
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return str.substring( 0, prevGraphemeClusterBreak( str, str.length-1 ) + 1 ); // eslint-disable-line max-len
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}
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// EXPORTS //
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module.exports = removeLast;
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