fix: preserve the fragment portion (hash) of the URL while redirecting (#108)

* fix: preserve the fragment portion (hash) of the URL while redirecting

Closes #107.

* refactor: extract hash as a variable for reuse

Author: 0x6b

src/no-dead-link.js

@@ -7,7 +7,7 @@ import { isAbsolute } from 'path';
 import { getURLOrigin } from 'get-url-origin';
 
 const DEFAULT_OPTIONS = {
-  checkRelative: true, // {boolean} `false` disables the checks for relative URIs
+  checkRelative: true, // {boolean} `false` disables the checks for relative URIs.
   baseURI: null, // {String|null} a base URI to resolve relative URIs.
   ignore: [], // {Array<String>} URIs to be skipped from availability checks.
   preferGET: [], // {Array<String>} origins to prefer GET over HEAD.
@@ -83,10 +83,11 @@ async function isAliveURI(uri, method = 'HEAD') {
         Object.assign({}, opts, { redirect: 'follow' }),
       );
 
+      const { hash } = URL.parse(uri);
       return {
         ok: finalRes.ok,
         redirected: true,
-        redirectTo: finalRes.url,
+        redirectTo: hash !== null ? `${finalRes.url}${hash}` : finalRes.url,
         message: `${res.status} ${res.statusText}`,
       };
     }

test/no-dead-link.js

@@ -86,6 +86,15 @@ tester.run('no-dead-link', rule, {
         ignoreRedirects: true,
       },
     },
+    {
+      text:
+        'should preserve hash while ignoring redirect: [BDD](http://mochajs.org/#bdd)',
+      output:
+        'should preserve hash while ignoring redirect: [BDD](http://mochajs.org/#bdd)',
+      options: {
+        ignoreRedirects: true,
+      },
+    },
   ],
   invalid: [
     {
@@ -187,5 +196,20 @@ tester.run('no-dead-link', rule, {
         },
       ],
     },
+    {
+      text:
+        'should preserve hash while redirecting: [BDD](http://mochajs.org/#bdd)',
+      output:
+        'should preserve hash while redirecting: [BDD](https://mochajs.org/#bdd)',
+      errors: [
+        {
+          message:
+            'http://mochajs.org/#bdd is redirected to https://mochajs.org/#bdd. (301 Moved Permanently)',
+          index: 46,
+          line: 1,
+          column: 47,
+        },
+      ],
+    },
   ],
 });