219 lines
4.7 KiB
Markdown
219 lines
4.7 KiB
Markdown
<!--
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@license Apache-2.0
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Copyright (c) 2021 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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# ltrimN
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> Trim `n` characters from the end of a string.
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<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
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<section class="intro">
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</section>
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<!-- /.intro -->
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<!-- Package usage documentation. -->
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<section class="usage">
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## Usage
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```javascript
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var ltrimN = require( '@stdlib/string/left-trim-n' );
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```
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#### ltrimN( str, n\[, chars] )
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Trims `n` characters from the beginning of a string.
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```javascript
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var str = ' foo ';
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var out = ltrimN( str, str.length );
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// returns 'foo '
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out = ltrimN( str, 1 );
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// returns ' foo '
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```
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By default, the function trims whitespace characters. To trim a different set of characters instead, provide a string or an array of characters to trim:
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```javascript
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var str = '🐶🐶🐶 Animals 🐶🐶🐶';
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var out = ltrimN( str, str.length, [ '🐶', ' ' ] );
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// returns 'Animals 🐶🐶🐶'
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out = ltrimN( str, str.length, '🐶 ' );
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// returns 'Animals 🐶🐶🐶'
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```
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</section>
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<!-- /.usage -->
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<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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</section>
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<!-- /.notes -->
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<!-- Package usage examples. -->
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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 ltrimN = require( '@stdlib/string/left-trim-n' );
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var out = ltrimN( ' Whitespace ', 3 );
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// returns 'Whitespace '
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out = ltrimN( '\t\t\tTabs\t\t\t', 2 );
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// returns '\tTabs\t\t\t'
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out = ltrimN( '~~~CUSTOM~~~', 3, '~' );
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// returns 'CUSTOM~~~'
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```
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</section>
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<!-- /.examples -->
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<!-- Section for describing a command-line interface. -->
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* * *
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<section class="cli">
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## CLI
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<!-- CLI usage documentation. -->
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<section class="usage">
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### Usage
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```text
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Usage: ltrimn [options] --n=<number>
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Options:
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-h, --help Print this message.
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-V, --version Print the package version.
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--n number Number of characters to trim.
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--chars str Characters to trim. Default: whitespace.
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--split sep Delimiter for stdin data. Default: '/\\r?\\n/'.
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```
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</section>
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<!-- /.usage -->
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<!-- CLI usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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### Notes
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- If the split separator is a [regular expression][mdn-regexp], ensure that the `split` option is either properly escaped or enclosed in quotes.
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```bash
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# Not escaped...
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$ echo -n $' foo \n bar \n' | ltrimn --split /\r?\n/
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# Escaped...
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$ echo -n $' foo \n bar \n' | ltrimn --split /\\r?\\n/
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```
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- The implementation ignores trailing delimiters.
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</section>
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<!-- /.notes -->
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<!-- CLI usage examples. -->
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<section class="examples">
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### Examples
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```bash
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$ ltrimn ' Whitespace ' --n=3
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Whitespace
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```
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To use as a [standard stream][standard-streams],
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```bash
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$ echo -n '~~~beep~boop~' | ltrimn --n=2 --chars '~'
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~beep~boop~
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```
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By default, when used as a [standard stream][standard-streams], the implementation assumes newline-delimited data. To specify an alternative delimiter, set the `split` option.
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```bash
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$ echo -n '~~~foo~~~\t~~~bar~~~\t~~~baz~~~' | ltrimn --split '\t' --chars '~' --n=3
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foo~~~
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bar~~~
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baz~~~
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```
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</section>
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<!-- /.examples -->
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</section>
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<!-- /.cli -->
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<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="references">
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</section>
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<!-- /.references -->
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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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[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
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[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams
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</section>
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<!-- /.links -->
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