value to test
boolean indicating whether a value is a regular expression string
var bool = isRegExpString( '/beep/' );
// returns true
var bool = isRegExpString( '/beep/gim' );
// returns true
var bool = isRegExpString( 'beep' );
// returns false
var bool = isRegExpString( '' );
// returns false
var bool = isRegExpString( null );
// returns false
Tests if a value is a regular expression string.