url: expose pathToFileURL and fileURLToPath

doc/api/url.md

@@ -921,6 +921,59 @@ console.log(url.format(myURL, { fragment: false, unicode: true, auth: false }));
 // Prints 'https://你好你好/?abc'
 ```
 
+### url.pathToFileURL(path)
+
+* `path` {string} The absolute path to convert to a File URL.
+* Returns: {URL} The file URL object.
+
+This function ensures the correct encodings of URL control characters in file
+paths when converting into File URLs.
+
+For example, the following errors can occur when converting from paths to URLs:
+
+```js
+// throws for missing schema (posix)
+// (in Windows the drive letter is detected as the protocol)
+new URL(__filename);
+
+// 'file:///foo' instead of the correct 'file:///foo%231' (posix)
+new URL('./foo#1', 'file:///');
+
+// 'file:///nas/foo.txt' instead of the correct 'file:///foo.txt' (posix)
+new URL(`file://${'//nas/foo.txt'}`);
+
+// 'file:///some/path%' instead of the correct 'file:///some/path%25' (posix)
+new URL(`sfile:${'/some/path%.js'}`);
+```
+
+where using `pathToFileURL` we can get the correct results above.
+
+### url.fileURLToPath(url)
+
+* `url` {URL} | {string} The file URL string or URL object to convert to a path.
+* Returns: {URL} The fully-resolved platform-specific Node.js file path.
+
+This function ensures the correct decodings of percent-encoded characters as
+well as ensuring a cross-platform valid absolute path string.
+
+When converting from URL to path, the following common errors can occur:
+
+```js
+// '/C:/path/' instead of 'C:\path\' (Windows)
+new URL('file:///C:/path/').pathname;
+
+// '/foo.txt' instead of '\\nas\foo.txt' (Windows)
+new URL('file://nas/foo.txt').pathname;
+
+// '/%E4%BD%A0%E5%A5%BD.txt' instead of '/你好.txt' (posix)
+new URL('file:///你好.txt').pathname;
+
+// '/hello%20world.txt' instead of '/hello world.txt' (posix)
+new URL('file:///hello world.txt').pathname;
+```
+
+where using `fileURLToPath` we can get the correct results above.
+
 ## Legacy URL API
 
 ### Legacy `urlObject`