# isURI
> Test if a value is a [URI][uri].
## Usage
```javascript
var isURI = require( '@stdlib/assert/is-uri' );
```
#### isURI( value )
Tests if a `value` is a [URI][uri].
```javascript
var bool = isURI( 'https://google.com' );
// returns true
bool = isURI( 'ftp://ftp.is.co.za/rfc/rfc1808.txt' );
// returns true
bool = isURI( '' );
// returns false
bool = isURI( 'foo' );
// returns false
bool = isURI( null );
// returns false
bool = isURI( NaN );
// returns false
bool = isURI( true );
// returns false
```
## Notes
- For more information regarding the URI scheme, see [RFC 3986][rfc-3986] and [Wikipedia][uri].
- On the distinction between URI, URL, and URN, see [The Difference Between URLs and URIs][difference-url-uri].
## Examples
```javascript
var isURI = require( '@stdlib/assert/is-uri' );
/* Valid */
var bool = isURI( 'http://google.com' );
// returns true
bool = isURI( 'http://localhost/' );
// returns true
bool = isURI( 'http://example.w3.org/path%20with%20spaces.html' );
// returns true
bool = isURI( 'http://example.w3.org/%20' );
// returns true
bool = isURI( 'ftp://ftp.is.co.za/rfc/rfc1808.txt' );
// returns true
bool = isURI( 'ftp://ftp.is.co.za/../../../rfc/rfc1808.txt' );
// returns true
bool = isURI( 'http://www.ietf.org/rfc/rfc2396.txt' );
// returns true
bool = isURI( 'ldap://[2001:db8::7]/c=GB?objectClass?one' );
// returns true
bool = isURI( 'mailto:John.Doe@example.com' );
// returns true
bool = isURI( 'news:comp.infosystems.www.servers.unix' );
// returns true
bool = isURI( 'tel:+1-816-555-1212' );
// returns true
bool = isURI( 'telnet://192.0.2.16:80/' );
// returns true
bool = isURI( 'urn:oasis:names:specification:docbook:dtd:xml:4.1.2' );
// returns true
/* Invalid */
// No scheme:
bool = isURI( '' );
// returns false
// No scheme:
bool = isURI( 'foo' );
// returns false
// No scheme:
bool = isURI( 'foo@bar' );
// returns false
// No scheme:
bool = isURI( '://foo/' );
// returns false
// Illegal characters:
bool = isURI( 'http://' );
// returns false
// Invalid path:
bool = isURI( 'http:////foo.html' );
// returns false
// Incomplete hex escapes...
bool = isURI( 'http://example.w3.org/%a' );
// returns false
bool = isURI( 'http://example.w3.org/%a/foo' );
// returns false
bool = isURI( 'http://example.w3.org/%at' );
// returns false
```
* * *
## CLI
### Usage
```text
Usage: is-uri [options] []
Options:
-h, --help Print this message.
-V, --version Print the package version.
```
### Examples
```bash
$ is-uri http://google.com
true
```
To use as a [standard stream][standard-streams],
```bash
$ echo -n 'http://google.com' | is-uri
true
```
[uri]: http://en.wikipedia.org/wiki/URI_scheme
[rfc-3986]: https://tools.ietf.org/html/rfc3986
[difference-url-uri]: https://danielmiessler.com/study/url-uri/
[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams