# Decimal Number
> [Regular expression][mdn-regexp] to match a decimal number.
## Usage
```javascript
var reDecimalNumber = require( '@stdlib/regexp/decimal-number' );
```
#### reDecimalNumber( \[options] )
Returns a [regular expression][mdn-regexp] to match a decimal number.
```javascript
var RE_DECIMAL_NUMBER = reDecimalNumber();
var out = RE_DECIMAL_NUMBER.test( 'foo 1.234.' );
// returns true
out = RE_DECIMAL_NUMBER.test( '2:3' );
// returns false
```
The function accepts an `options` object with optional properties:
- **flags**: `string` specifying regular expression [flags][mdn-regexp-flags]. Default: `''`.
- **capture**: `boolean` indicating whether to create a capture group for the match. Default: `false`.
By default, the function returns a regular expression which does not have any flags specified. To specify [flags][mdn-regexp-flags], set the `flags` option with a list of flags (which may be in any order).
```javascript
var replace = require( '@stdlib/string/replace' );
var RE_DECIMAL_NUMBER = reDecimalNumber({
'flags': 'g'
});
var str = 'beep 1.234 boop 1.234';
var out = replace( str, RE_DECIMAL_NUMBER, '' );
// returns 'beep boop '
```
By default, the function returns a regular expression which does not capture the part of a string matching the regular expression. To capture matches, set the `capture` option.
```javascript
var RE_DECIMAL_NUMBER = reDecimalNumber({
'capture': true
});
var out = RE_DECIMAL_NUMBER.exec( 'beep 1.234 boop' ).slice();
// returns [ '1.234', '1.234' ]
out = RE_DECIMAL_NUMBER.exec( '' );
// returns null
```
#### reDecimalNumber.REGEXP
[Regular expression][mdn-regexp] to match a decimal number.
```javascript
var bool = reDecimalNumber.REGEXP.test( '2:3' );
// returns false
```
#### reDecimalNumber.REGEXP_CAPTURE
[Regular expression][mdn-regexp] to capture characters matching a decimal number.
```javascript
var parts = reDecimalNumber.REGEXP_CAPTURE.exec( '1.234' );
// returns [ '1.234', '1.234' ]
```
## Notes
- A leading digit is not required.
```javascript
var bool = reDecimalNumber.REGEXP.test( '.5' );
// returns true
```
- A decimal point and at least one trailing digit is required.
```javascript
var bool = reDecimalNumber.REGEXP.test( '5.' );
// returns false
```
- The `REGEXP` regular expression is defined as
```text
/[-+]{0,1}[0-9]*\.[0-9]+/
```
- The `REGEXP_CAPTURE` regular expression is defined as
```text
/([-+]{0,1}[0-9]*\.[0-9]+)/
```
## Examples
```javascript
var reDecimalNumber = require( '@stdlib/regexp/decimal-number' );
var RE_DECIMAL_NUMBER = reDecimalNumber();
var bool = RE_DECIMAL_NUMBER.test( '1.234' );
// returns true
bool = RE_DECIMAL_NUMBER.test( 'beep 1.234' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '1.234 boop' );
// returns true
bool = RE_DECIMAL_NUMBER.test( 'foo 1.234.' );
// returns true
bool = RE_DECIMAL_NUMBER.test( 'foo 1.234.567.890' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '1.234!' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '0.234' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '.234' );
// returns true
bool = RE_DECIMAL_NUMBER.test( 'beep .234' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '.234 boop' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '1.0' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '-1.0' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '+1.0' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '0.0' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '.0' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '1.234:' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '1.234%' );
// returns true
bool = RE_DECIMAL_NUMBER.test( '0' );
// returns false
bool = RE_DECIMAL_NUMBER.test( 'beep 0' );
// returns false
bool = RE_DECIMAL_NUMBER.test( '2:3' );
// returns false
bool = RE_DECIMAL_NUMBER.test( 'beep' );
// returns false
bool = RE_DECIMAL_NUMBER.test( '' );
// returns false
```
[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
[mdn-regexp-flags]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#advanced_searching_with_flags_2