Add a base_url property to JS::RequreRemote to specify the base URL for resolving relative paths.

packages/gems/js/lib/js/require_remote.rb

@@ -43,11 +43,27 @@ class RequireRemote
     include Singleton
 
     def initialize
+      # By default, the base_url is the URL of the HTML file that invoked ruby.wasm vm.
       base_url = JS.global[:URL].new(JS.global[:location][:href])
       @resolver = URLResolver.new(base_url)
       @evaluator = Evaluator.new
     end
 
+    # If you want to resolve relative paths to a starting point other than the HTML file that executes ruby.wasm,
+    # you can set the base_url property.
+    # For example, if you want to use the `lib` directory as the starting point, specify base_url as follows
+    #
+    # == Example
+    #  require 'js/require_remote'
+    #  JS::RequireRemote.instance.base_url = "lib"
+    #  JS::RequireRemote.instance.load("foo") # => 'lib/foo.rb' will be loaded.
+    #
+    def base_url=(base_url)
+      base_url = base_url.end_with?("/") ? base_url : "#{base_url}/"
+      url = JS.global[:URL].new(base_url, JS.global[:location][:href])
+      @resolver = URLResolver.new(url)
+    end
+
     # Load the given feature from remote.
     def load(relative_feature)
       location = @resolver.get_location(relative_feature)

packages/gems/js/lib/js/require_remote/url_resolver.rb

@@ -26,6 +26,10 @@ def pop()
         @url_stack.pop
       end
 
+      def inspect
+        "#{self.class}(#{@url_stack})"
+      end
+
       private
 
       def filename_from(relative_feature)

packages/npm-packages/ruby-wasm-wasi/test-e2e/integrations/js-require-remote.spec.ts

@@ -115,5 +115,25 @@ if (!process.env.RUBY_NPM_PACKAGE_ROOT) {
 
       expect(await resolve()).toBe("Hello from RecursiveRequire::B");
     });
+
+    test("JS::RequireRemote#load loads the file with a path relative to the base_url specified by the base_url property.", async ({
+      page,
+    }) => {
+      const resolve = await resolveBinding(page, "checkResolved");
+      await page.goto(
+        "https://cdn.jsdelivr.net/npm/@ruby/head-wasm-wasi@latest/dist/",
+      );
+      await page.setContent(`
+      <script src="browser.script.iife.js"></script>
+      <script type="text/ruby" data-eval="async">
+        require 'js/require_remote'
+        JS::RequireRemote.instance.base_url = 'fixtures/recursive_require'
+        JS::RequireRemote.instance.load 'b'
+        JS.global.checkResolved RecursiveRequire::B.new.message
+      </script>
+     `);
+
+      expect(await resolve()).toBe("Hello from RecursiveRequire::B");
+    });
   });
 }