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feat: add string/base/first
This commit adds "base" support for returning the first `n` Unicode code units of a provided string.
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‎lib/node_modules/@stdlib/string/base/first/README.md

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<!--
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@license Apache-2.0
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Copyright (c) 2023 The Stdlib Authors.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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# first
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> Return the first `n` Unicode code units of a string.
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<section class="usage">
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## Usage
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```javascript
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var first = require( '@stdlib/string/base/first' );
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```
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#### first( str, n )
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Returns the first `n` Unicode code units of a string.
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```javascript
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var out = first( 'last man standing', 1 );
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// returns 'l'
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out = first( 'Hidden Treasures', 1 );
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// returns 'H'
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out = first( 'foo bar', 5 );
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// returns 'foo b'
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out = first( 'foo bar', 10 );
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// returns 'foo bar'
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```
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</section>
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<!-- /.usage -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var first = require( '@stdlib/string/base/first' );
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var str = first( 'presidential election', 1 );
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// returns 'p'
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str = first( 'JavaScript', 1 );
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// returns 'J'
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str = first( 'The Last of the Mohicans', 5 );
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// returns 'The L'
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```
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</section>
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<!-- /.examples -->
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<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
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<section class="related">
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</section>
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<!-- /.related -->
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<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="links">
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</section>
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<!-- /.links -->

‎lib/node_modules/@stdlib/string/base/first/benchmark/benchmark.js

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2023 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 bench = require( '@stdlib/bench' );
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var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
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var pkg = require( './../package.json' ).name;
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var first = require( './../lib' );
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// MAIN //
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bench( pkg, function benchmark( b ) {
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var values;
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var out;
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var i;
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values = [
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'beep boop',
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'foo bar',
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'xyz abc',
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'🐶🐮🐷🐰🐸'
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];
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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out = first( values[ i%values.length ], 1 );
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if ( typeof out !== 'string' ) {
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b.fail( 'should return a string' );
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}
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}
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b.toc();
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if ( !isString( out ) ) {
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b.fail( 'should return a string' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});

‎lib/node_modules/@stdlib/string/base/first/docs/repl.txt

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{{alias}}( str, n )
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Returns the first `n` Unicode code units of a string.
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Parameters
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----------
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str: string
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Input string.
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n: integer
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Number of Unicode code units to return.
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Returns
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-------
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out: string
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Output string.
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Examples
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--------
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> var out = {{alias}}( 'beep', 1 )
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'b'
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> out = {{alias}}( 'Boop', 1 )
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'B'
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> out = {{alias}}( 'foo bar', 5 )
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'foo b'
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See Also
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--------
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‎lib/node_modules/@stdlib/string/base/first/docs/types/index.d.ts

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/*
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* @license Apache-2.0
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*
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* Copyright (c) 2023 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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// TypeScript Version: 2.0
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/**
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* Returns the first `n` Unicode code units of a string.
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*
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* @param str - input string
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* @param n - number of code units to return
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* @returns output string
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*
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* @example
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* var out = first( 'last man standing', 1 );
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* // returns 'l'
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*
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* @example
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* var out = first( 'presidential election', 1 );
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* // returns 'p'
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*
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* @example
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* var out = first( 'JavaScript', 1 );
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* // returns 'J'
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*
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* @example
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* var out = first( 'Hidden Treasures', 1 );
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* // returns 'H'
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*
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* @example
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* var out = first( 'foo bar', 5 );
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* // returns 'foo b'
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*/
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declare function first( str: string, n: number ): string;
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// EXPORTS //
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export = first;

‎lib/node_modules/@stdlib/string/base/first/docs/types/test.ts

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/*
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* @license Apache-2.0
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*
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* Copyright (c) 2023 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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import first = require( './index' );
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// TESTS //
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// The function returns a string...
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{
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first( 'abc', 1 ); // $ExpectType string
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}
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// The compiler throws an error if the function is provided a value other than a string...
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{
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first( true, 1 ); // $ExpectError
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first( false, 1 ); // $ExpectError
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first( null, 1 ); // $ExpectError
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first( undefined, 1 ); // $ExpectError
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first( 5, 1 ); // $ExpectError
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first( [], 1 ); // $ExpectError
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first( {}, 1 ); // $ExpectError
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first( ( x: number ): number => x, 1 ); // $ExpectError
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}
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// The compiler throws an error if the function is provided a second argument that is not a number...
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{
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first( 'abc', true ); // $ExpectError
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first( 'abc', false ); // $ExpectError
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first( 'abc', null ); // $ExpectError
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first( 'abc', 'abc' ); // $ExpectError
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first( 'abc', [] ); // $ExpectError
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first( 'abc', {} ); // $ExpectError
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first( 'abc', ( x: number ): number => x ); // $ExpectError
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}
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// The compiler throws an error if the function is provided an unsupported number of arguments...
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{
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first(); // $ExpectError
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first( 'abc' ); // $ExpectError
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first( 'abc', 1, 2 ); // $ExpectError
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}

‎lib/node_modules/@stdlib/string/base/first/examples/index.js

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2023 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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var first = require( './../lib' );
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console.log( first( 'presidential election', 1 ) );
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// => 'p'
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console.log( first( 'JavaScript', 1 ) );
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// => 'J'
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console.log( first( 'The Last of the Mohicans', 5 ) );
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// => 'The L'

‎lib/node_modules/@stdlib/string/base/first/lib/index.js

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2023 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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/**
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* Return the first `n` Unicode code units of a string.
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*
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* @module @stdlib/string/base/first
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*
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* @example
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* var first = require( '@stdlib/string/base/first' );
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*
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* var out = first( 'last man standing', 1 );
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* // returns 'l'
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*
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* out = first( 'Hidden Treasures', 1 );
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* // returns 'H';
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*/
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// MODULES //
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var main = require( './main.js' );
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// EXPORTS //
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module.exports = main;

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