fix: stop adding trailing / to absolute urls

packages/render/src/helpers/__tests__/normalizeResourceLocator.test.ts

@@ -42,6 +42,21 @@ describe('normalizeResourceLocator', () => {
       normalizeResourceLocator('//bar.com/baz', 'https://foo.com/')
     ).toEqual('https://bar.com/baz');
   });
+  it('should not append a trailing slash to an absolute URL with a path (issue #47)', () => {
+    expect(
+      normalizeResourceLocator('https://example.com/files/report.pdf')
+    ).toEqual('https://example.com/files/report.pdf');
+  });
+  it('should return an absolute URL untouched even when a base URL is provided (issue #47)', () => {
+    expect(
+      normalizeResourceLocator('https://bit.ly/abc123', 'https://foo.com/')
+    ).toEqual('https://bit.ly/abc123');
+  });
+  it('should preserve query and fragment on an absolute URL (issue #47)', () => {
+    expect(
+      normalizeResourceLocator('https://example.com/a/b?q=1#frag')
+    ).toEqual('https://example.com/a/b?q=1#frag');
+  });
   it('should pass regression #', () => {
     expect(
       normalizeResourceLocator(

packages/render/src/helpers/normalizeResourceLocator.ts

@@ -1,3 +1,10 @@
+/**
+ * Matches a URL that already carries a scheme, e.g. `https://`, `ftp://`.
+ * Protocol-relative URLs (`//host/path`) are intentionally excluded so they
+ * still get resolved against the base URL.
+ */
+const ABSOLUTE_URL_REGEX = /^[a-z][a-z0-9+.-]*:\/\//i;
+
 /**
  * This function normalize relative and protocol-relative URLs to absolute
  * URLs as per {@link https://tools.ietf.org/html/rfc1808 | RFC1808}.
@@ -10,6 +17,14 @@ export default function normalizeResourceLocator(
   baseUrl?: string
 ) {
   try {
+    // If the URL is already absolute, return it untouched. We deliberately
+    // avoid round-tripping through the URL constructor here because React
+    // Native's URL polyfill appends a trailing slash to a path-bearing URL
+    // (e.g. `https://example.com/file.pdf` -> `https://example.com/file.pdf/`),
+    // corrupting otherwise-valid links. See issue #47.
+    if (ABSOLUTE_URL_REGEX.test(url)) {
+      return url;
+    }
     if (!baseUrl) {
       // Try to parse as absolute URL
       return new URL(url).href;