# Function Name
> [Regular expression][regexp] to capture a function name.
## Usage
```javascript
var reFunctionName = require( '@stdlib/regexp/function-name' );
```
#### reFunctionName
Returns a [regular expression][regexp] to capture a `function` name.
```javascript
function beep() {
return 'boop';
}
var RE_FUNCTION_NAME = reFunctionName();
var str = RE_FUNCTION_NAME.exec( beep.toString() )[ 1 ];
// returns 'beep'
```
#### reFunctionName.REGEXP
[Regular expression][regexp] to capture a `function` name.
```javascript
var str = reFunctionName.REGEXP.exec( Math.sqrt.toString() )[ 1 ];
// returns 'sqrt'
```
## Examples
```javascript
var Int8Array = require( '@stdlib/array/int8' );
var reFunctionName = require( '@stdlib/regexp/function-name' );
var RE_FUNCTION_NAME = reFunctionName();
function fname( fcn ) {
return RE_FUNCTION_NAME.exec( fcn.toString() )[ 1 ];
}
var f = fname( Math.sqrt );
// returns 'sqrt'
f = fname( Int8Array );
// returns 'Int8Array'
f = fname( Object.prototype.toString );
// returns 'toString'
f = fname( function () {} );
// returns ''
```
[regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions