Change URL.port implementation to match WHATWG specifications (#4954)

Changed `URL.port` implementation to match [WHATWG
specifications](https://url.spec.whatwg.org/#port-state).

This PR matches the behaviour of other browsers:

1.  a `TypeError` must be thrown when passing an URL with an invalid
port to the constructor.

2. When setting an invalid port, using property setter, I haven't found
what should happen in this case, so I mimic **Firefox** & **Node**
behaviour. If an invalid port is set, it will use the previous value.
**Chrome** sets the value to `'0'` if an invalid port is set. I prefer
to keep the previous valid value.  (I can use Chrome's behaviour if you
think it's better, it's a simple value change)

```
url.port = '3000'; // valid
url.port = 'deno'; // invalid
assertEquals(url.port, '3000');
```

3. If the port value equals the current protocol default port value,
`port` will be an empty string.

2 files changed, 138 insertions, 5 deletions

diff --git a/cli/js/tests/url_test.ts b/cli/js/tests/url_test.ts
index e4d497ffb..e8348b206 100644
--- a/cli/js/tests/url_test.ts
+++ b/cli/js/tests/url_test.ts
@@ -212,3 +212,104 @@ unitTest(function createBadUrl(): void {
     new URL("0.0.0.0:8080");
   });
 });
+
+unitTest(function throwForInvalidPortConstructor(): void {
+  const urls = [
+    // If port is greater than 2^16 − 1, validation error, return failure.
+    `https://baz.qat:${2 ** 16}`,
+    "https://baz.qat:-32",
+    "https://baz.qat:deno",
+  ];
+
+  for (const url of urls) {
+    assertThrows(() => new URL(url));
+  }
+});
+
+unitTest(function doNotOverridePortIfInvalid(): void {
+  const initialPort = "3000";
+  const ports = [
+    // If port is greater than 2^16 − 1, validation error, return failure.
+    `${2 ** 16}`,
+    "-32",
+    "deno",
+  ];
+
+  for (const port of ports) {
+    const url = new URL(`https://deno.land:${initialPort}`);
+    url.port = port;
+    assertEquals(url.port, initialPort);
+  }
+});
+
+unitTest(function doNotOverridePortIfInvalid(): void {
+  const initialPort = "3000";
+  const ports = [
+    // If port is greater than 2^16 − 1, validation error, return failure.
+    `${2 ** 16}`,
+    "-32",
+    "deno",
+  ];
+
+  for (const port of ports) {
+    const url = new URL(`https://deno.land:${initialPort}`);
+    url.port = port;
+    assertEquals(url.port, initialPort);
+  }
+});
+
+unitTest(function emptyPortForSchemeDefaultPort(): void {
+  const nonDefaultPort = "3500";
+  const urls = [
+    { url: "ftp://baz.qat:21", port: "21", protocol: "ftp:" },
+    { url: "https://baz.qat:443", port: "443", protocol: "https:" },
+    { url: "wss://baz.qat:443", port: "443", protocol: "wss:" },
+    { url: "http://baz.qat:80", port: "80", protocol: "http:" },
+    { url: "ws://baz.qat:80", port: "80", protocol: "ws:" },
+    { url: "file://home/index.html", port: "", protocol: "file:" },
+    { url: "/foo", baseUrl: "ftp://baz.qat:21", port: "21", protocol: "ftp:" },
+    {
+      url: "/foo",
+      baseUrl: "https://baz.qat:443",
+      port: "443",
+      protocol: "https:",
+    },
+    {
+      url: "/foo",
+      baseUrl: "wss://baz.qat:443",
+      port: "443",
+      protocol: "wss:",
+    },
+    {
+      url: "/foo",
+      baseUrl: "http://baz.qat:80",
+      port: "80",
+      protocol: "http:",
+    },
+    { url: "/foo", baseUrl: "ws://baz.qat:80", port: "80", protocol: "ws:" },
+    {
+      url: "/foo",
+      baseUrl: "file://home/index.html",
+      port: "",
+      protocol: "file:",
+    },
+  ];
+
+  for (const { url: urlString, baseUrl, port, protocol } of urls) {
+    const url = new URL(urlString, baseUrl);
+    assertEquals(url.port, "");
+
+    url.port = nonDefaultPort;
+    assertEquals(url.port, nonDefaultPort);
+
+    url.port = port;
+    assertEquals(url.port, "");
+
+    // change scheme
+    url.protocol = "sftp:";
+    assertEquals(url.port, port);
+
+    url.protocol = protocol;
+    assertEquals(url.port, "");
+  }
+});
diff --git a/cli/js/web/url.ts b/cli/js/web/url.ts
index 374ddd252..77285e456 100644
--- a/cli/js/web/url.ts
+++ b/cli/js/web/url.ts
@@ -40,6 +40,17 @@ const searchParamsMethods: Array<keyof URLSearchParams> = [
   "set",
 ];
 
+// https://url.spec.whatwg.org/#special-scheme
+const schemePorts: { [key: string]: string } = {
+  ftp: "21",
+  file: "",
+  http: "80",
+  https: "443",
+  ws: "80",
+  wss: "443",
+};
+const MAX_PORT = 2 ** 16 - 1;
+
 function parse(url: string): URLParts | undefined {
   const urlMatch = urlRegExp.exec(url);
   if (urlMatch) {
@@ -178,6 +189,18 @@ export class URLImpl implements URL {
     urls.set(searchParams, this);
   };
 
+  #validatePort = (value: string): string | undefined => {
+    // https://url.spec.whatwg.org/#port-state
+    if (value === "") return value;
+
+    const port = parseInt(value, 10);
+
+    if (!Number.isNaN(port) && port > 0 && port <= MAX_PORT)
+      return port.toString();
+
+    return undefined;
+  };
+
   get hash(): string {
     return parts.get(this)!.hash;
   }
@@ -268,14 +291,17 @@ export class URLImpl implements URL {
   }
 
   get port(): string {
-    return parts.get(this)!.port;
+    const port = parts.get(this)!.port;
+    if (schemePorts[parts.get(this)!.protocol] === port) {
+      return "";
+    }
+
+    return port;
   }
 
   set port(value: string) {
-    const port = parseInt(String(value), 10);
-    parts.get(this)!.port = isNaN(port)
-      ? ""
-      : Math.max(0, port % 2 ** 16).toString();
+    const port = this.#validatePort(value);
+    parts.get(this)!.port = port ?? this.port;
   }
 
   get protocol(): string {
@@ -344,6 +370,11 @@ export class URLImpl implements URL {
       throw new TypeError("Invalid URL.");
     }
 
+    const { port } = (urlParts.protocol ? urlParts : baseParts) as URLParts;
+    if (this.#validatePort(port) === undefined) {
+      throw new TypeError("Invalid URL.");
+    }
+
     if (urlParts.protocol) {
       parts.set(this, urlParts);
     } else if (baseParts) {
@@ -360,6 +391,7 @@ export class URLImpl implements URL {
     } else {
       throw new TypeError("URL requires a base URL.");
     }
+
     this.#updateSearchParams();
   }