**isURL(str [, options])** | check if the string is an URL.<br/><br/>`options` is an object which defaults to `{ protocols: ['http','https','ftp'], require_tld: true, require_protocol: false, require_host: true, require_port: false, require_valid_protocol: true, allow_underscores: false, host_whitelist: false, host_blacklist: false, allow_trailing_dot: false, allow_protocol_relative_urls: false, allow_fragments: true, allow_query_components: true, disallow_auth: false, validate_length: true }`.<br/><br/>require_protocol - if set as true isURL will return false if protocol is not present in the URL.<br/>require_valid_protocol - isURL will check if the URL's protocol is present in the protocols option.<br/>protocols - valid protocols can be modified with this option.<br/>require_host - if set as false isURL will not check if host is present in the URL.<br/>require_port - if set as true isURL will check if port is present in the URL.<br/>allow_protocol_relative_urls - if set as true protocol relative URLs will be allowed.<br/>allow_fragments - if set as false isURL will return false if fragments are present.<br/>allow_query_components - if set as false isURL will return false if query components are present.<br/>validate_length - if set as false isURL will skip string length validation (2083 characters is IE max URL length).

**isUUID(str [, version])** | check if the string is a UUID (version 1, 2, 3, 4 or 5).

**isVariableWidth(str)** | check if the string contains a mixture of full and half-width chars.

**isWhitelisted(str, chars)** | checks characters if they appear in the whitelist.

**matches(str, pattern [, modifiers])** | check if string matches the pattern.<br/><br/>Either `matches('foo', /foo/i)` or `matches('foo', 'foo', 'i')`.