Break off query string when comparing url for sidebar

src/front-end/templates/toc.js.hbs

@@ -10,7 +10,7 @@ class MDBookSidebarScrollbox extends HTMLElement {
     connectedCallback() {
         this.innerHTML = '{{#toc}}{{/toc}}';
         // Set the current, active page, and reveal it if it's hidden
-        let current_page = document.location.href.toString().split("#")[0];
+        let current_page = document.location.href.toString().split("#")[0].split("?")[0];
         if (current_page.endsWith("/")) {
             current_page += "index.html";
         }

tests/gui/sidebar-active.goml

@@ -0,0 +1,17 @@
+// This GUI test checks the active page sidebar highlight.
+
+go-to: |DOC_PATH| + "index.html"
+
+assert-text: ("mdbook-sidebar-scrollbox a.active", "Prefix Chapter")
+
+go-to: |DOC_PATH| + "individual/index.html"
+
+assert-text: ("mdbook-sidebar-scrollbox a.active", "3. Markdown Individual tags")
+
+go-to: |DOC_PATH| + "index.html?highlight=test"
+
+assert-text: ("mdbook-sidebar-scrollbox a.active", "Prefix Chapter")
+
+go-to: |DOC_PATH| + "individual/index.html?highlight=test"
+
+assert-text: ("mdbook-sidebar-scrollbox a.active", "3. Markdown Individual tags")