51 lines
1.3 KiB
JavaScript
51 lines
1.3 KiB
JavaScript
/**
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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 RE_EXTNAME = require( '@stdlib/regexp/extname' ).REGEXP;
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// MAIN //
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/**
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* Returns a filename extension.
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*
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* @param {string} filename - filename
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* @throws {TypeError} must provide a string primitive
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* @returns {string} filename extension
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*
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* @example
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* var ext = extname( 'index.js' );
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* // returns '.js'
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*/
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function extname( filename ) {
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if ( !isString( filename ) ) {
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throw new TypeError( 'invalid argument. Filename must be a primitive string. Value: `' + filename + '`.' );
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}
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return RE_EXTNAME.exec( filename )[ 1 ];
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}
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// EXPORTS //
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module.exports = extname;
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