@stdlib/string/replace-before/README.md

String manipulation functions.

<!--

@license Apache-2.0

Copyright (c) 2023 The Stdlib Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

-->

# replaceBefore

> Replace the substring before the first occurrence of a specified search string.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="usage">

## Usage

```javascript
var replaceBefore = require( '@stdlib/string/replace-before' );
```

#### replaceBefore( str, search, replacement )

Replaces the substring before the first occurrence of a specified search string.

```javascript
var out = replaceBefore( 'beep boop', ' ', 'loop' );
// returns 'loop boop'

out = replaceBefore( 'beep boop', 'o', 'bar' );
// returns 'baroop'
```

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   If a search string is not present in a provided string, the function returns the provided string unchanged.
-   If a search string is an empty string, the function returns the provided string unchanged.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var replaceBefore = require( '@stdlib/string/replace-before' );

var out = replaceBefore( 'beep boop', 'p', 'see' );
// returns 'seep boop'

out = replaceBefore( 'Hello World!', 'xyz', 'foo' );
// returns 'Hello World!'

out = replaceBefore( 'Hello World!', '', 'foo' );
// returns 'Hello World!'

out = replaceBefore( '', 'xyz', 'foo' );
// returns ''
```

</section>

<!-- /.examples -->

<!-- Section for describing a command-line interface. -->

* * *

<section class="cli">

## CLI

<!-- CLI usage documentation. -->

<section class="usage">

### Usage

```text
Usage: replace-before [options] --search=<string> --replacement=<string> [<string>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --search string       Search string.
         --replacement string  Replacement string.
         --split sep           Delimiter for stdin data. Default: '/\\r?\\n/'.
```

</section>

<!-- /.usage -->

<!-- CLI usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

### Notes

-   If the split separator is a [regular expression][mdn-regexp], ensure that the `split` option is either properly escaped or enclosed in quotes.

    ```bash
    # Not escaped...
    $ echo -n $'foo\nbar\nbaz' | replace-before --search a --replacement b --split /\r?\n/

    # Escaped...
    $ echo -n $'foo\nbar\nbaz' | replace-before --search a --replacement b --split /\\r?\\n/
    ```

-   The implementation ignores trailing delimiters.

</section>

<!-- /.notes -->

<!-- CLI usage examples. -->

<section class="examples">

### Examples

```bash
$ replace-before abcdefg --search d --replacement pqr
pqrdefg
```

To use as a [standard stream][standard-streams],

```bash
$ echo -n $'beep\nboop' | replace-before --search p --replacement see
seep
seep
```

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.

```bash
$ echo -n 'beep\tboop' | replace-before --search p --replacement see --split '\t'
seep
seep
```

</section>

<!-- /.examples -->

</section>

<!-- /.cli -->

<!-- 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. -->

<section class="references">

</section>

<!-- /.references -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams

[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

</section>

<!-- /.links -->