# constantcase
> Returns a string converted to a constant case.
## Usage
```javascript
var constantcase = require( '@stdlib/string/constantcase' );
```
#### constantcase( str )
Converts a string to constant case.
```javascript
var str = constantcase( 'foo bar' );
// returns 'FOO_BAR'
str = constantcase( 'foo bar baz' );
// returns 'FOO_BAR_BAZ'
str = constantcase( 'foo_bar' );
// returns 'FOO_BAR'
```
## Examples
```javascript
var constantcase = require( '@stdlib/string/constantcase' );
var str = 'Hello World!';
var out = constantcase( str );
// returns 'HELLO_WORLD'
str = 'I am a tiny little teapot';
out = constantcase( str );
// returns 'I_AM_A_TINY_LITTLE_TEAPOT'
str = 'with big problems';
out = constantcase( str );
// returns 'WITH_BIG_PROBLEMS'
str = 'To be, or not to be: that is the question.';
out = constantcase( str );
// returns 'TO_BE_OR_NOT_TO_BE_THAT_IS_THE_QUESTION'
str = 'isMobile';
out = constantcase( str );
// returns 'IS_MOBILE'
```
* * *
## CLI
### Usage
```text
Usage: constantcase [options] []
Options:
-h, --help Print this message.
-V, --version Print the package version.
--split sep Delimiter for stdin data. Default: '/\\r?\\n/'.
```
### 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 $'beEp booP\nisMobile' | constantcase --split /\r?\n/
# Escaped...
$ echo -n $'beEp booP\nisMobile' | constantcase --split /\\r?\\n/
```
- The implementation ignores trailing delimiters.
### Examples
```bash
$ constantcase 'hello world'
HELLO_WORLD
```
To use as a [standard stream][standard-streams],
```bash
$ echo -n 'beEp booP' | constantcase
BEEP_BOOP
```
To use as a [standard stream][standard-streams],
```bash
$ echo -n 'isMobile' | constantcase
IS_MOBILE
```
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_boop\tisMobile' | constantcase --split '\t'
BEEP_BOOP
IS_MOBILE
```
[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams
[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
[@stdlib/string/camelcase]: https://github.com/stdlib-js/string/tree/main/camelcase
[@stdlib/string/kebabcase]: https://github.com/stdlib-js/string/tree/main/kebabcase
[@stdlib/string/pascalcase]: https://github.com/stdlib-js/string/tree/main/pascalcase
[@stdlib/string/snakecase]: https://github.com/stdlib-js/string/tree/main/snakecase