194 lines
4.2 KiB
Markdown
194 lines
4.2 KiB
Markdown
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<!--
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@license Apache-2.0
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Copyright (c) 2018 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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# Left Trim
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> Trim whitespace characters from the beginning 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 ltrim = require( '@stdlib/string/left-trim' );
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```
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#### ltrim( str )
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Trims whitespace from the beginning of a `string`.
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```javascript
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var out = ltrim( ' \r\n\t Beep \t\t\n ' );
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// returns 'Beep \t\t\n '
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```
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</section>
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<!-- /.usage -->
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<section class="notes">
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## Notes
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- Following [Unicode 6.3.0][unicode] and later, "whitespace" is defined as the following characters: `[ \\f\\n\\r\\t\\v\\u0020\\u00a0\\u1680\\u2000-\\u200a\\u2028\\u2029\\u202f\\u205f\\u3000\\ufeff]`.
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</section>
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<!-- /.notes -->
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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 ltrim = require( '@stdlib/string/left-trim' );
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var str = ltrim( ' Whitespace ' );
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// returns 'Whitespace '
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str = ltrim( '\t\t\tTabs\t\t\t' );
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// returns 'Tabs\t\t\t'
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str = ltrim( '\n\n\nNew Lines\n\n\n' );
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// returns 'New Lines\n\n\n'
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```
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</section>
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<!-- /.examples -->
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* * *
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<section class="cli">
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## CLI
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<section class="usage">
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### Usage
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```text
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Usage: ltrim [options] [<string>]
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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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--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 $' foo \n bar ' | ltrim --split /\r?\n/
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# Escaped...
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$ echo -n $' foo \n bar ' | ltrim --split /\\r?\\n/
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```
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- The implementation ignores trailing delimiters.
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</section>
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<!-- /.notes -->
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<section class="examples">
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### Examples
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```bash
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$ ltrim ' beep boop'
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beep boop
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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' | ltrim
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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 ' | ltrim --split '\t'
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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 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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* * *
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## See Also
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- <span class="package-name">[`@stdlib/string/trim`][@stdlib/string/trim]</span><span class="delimiter">: </span><span class="description">trim whitespace characters from the beginning and end of a string.</span>
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- <span class="package-name">[`@stdlib/string/right-trim`][@stdlib/string/right-trim]</span><span class="delimiter">: </span><span class="description">trim whitespace characters from the end of a string.</span>
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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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[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams
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[unicode]: https://en.wikipedia.org/wiki/Unicode
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[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
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<!-- <related-links> -->
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[@stdlib/string/trim]: https://github.com/stdlib-js/string/tree/main/trim
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[@stdlib/string/right-trim]: https://github.com/stdlib-js/string/tree/main/right-trim
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<!-- </related-links> -->
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</section>
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<!-- /.links -->
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