Function Name

Determine a function's name.

Usage

var functionName = require( '@stdlib/utils/function-name' );

functionName( fcn )

Returns the name of a function.

var v = functionName( Math.sqrt );
// returns 'sqrt'

If provided an anonymous function, the function returns an empty string or the string "anonymous".

var v = functionName( function () {} );
// returns '' || 'anonymous'

If provided a value which is not a function, the function throws a TypeError.

try {
    functionName( 'beep' );
    // throws error...
} catch ( err ) {
    console.error( err );
}

Notes

For more information regarding the naming of anonymous functions, see
- Function Names in ES6
- Webkit bug 7726
- MDN

Examples

var Float64Array = require( '@stdlib/array/float64' );
var Buffer = require( '@stdlib/buffer/ctor' );
var Number = require( '@stdlib/number/ctor' );
var functionName = require( '@stdlib/utils/function-name' );

var v = functionName( Math.sqrt );
// returns 'sqrt'

v = functionName( Float64Array );
// returns 'Float64Array'

v = functionName( Buffer );
// returns 'Buffer'

v = functionName( Date );
// returns 'Date'

v = functionName( String );
// returns 'String'

v = functionName( Boolean );
// returns 'Boolean'

v = functionName( Function );
// returns 'Function'

v = functionName( Number );
// returns 'Number'

v = functionName( function foo() {} );
// returns 'foo'

v = functionName( function () {} );
// returns '' || 'anonymous'