Fix race condition by hiding Build Now button until JS is ready

Author: LakshyaBagani

core/src/main/resources/lib/hudson/project/configurable.jelly

@@ -32,7 +32,9 @@ THE SOFTWARE.
         <st:adjunct includes="lib.hudson.project.configurable.configurable"/>
         <j:set var="buildUrl" value="${url}/build?delay=0sec"/>
         <j:set var="taskHref" value="${it.parameterized ? buildUrl : '#'}"/>
-        <l:task href="${taskHref}" data-task-href="${buildUrl}" icon="icon-clock icon-md" permission="${it.BUILD}" post="${!it.parameterized}" data-callback="lib_hudson_project_configurable_build_now_callback" data-task-failure="${%buildFailed}" data-task-success="${%Build scheduled}" data-parameterized="${it.parameterized}" title="${it.buildNowText}"/>
+        <div id="build-now-container" style="display: none;">
+          <l:task href="${taskHref}" data-task-href="${buildUrl}" icon="icon-clock icon-md" permission="${it.BUILD}" post="${!it.parameterized}" data-callback="lib_hudson_project_configurable_build_now_callback" data-task-failure="${%buildFailed}" data-task-success="${%Build scheduled}" data-parameterized="${it.parameterized}" title="${it.buildNowText}"/>
+        </div>
       </j:if>
       <j:choose>
         <j:when test="${h.hasPermission(it,it.CONFIGURE)}">

core/src/main/resources/lib/hudson/project/configurable/configurable.js

@@ -24,4 +24,25 @@
     }
   }
   window.lib_hudson_project_configurable_build_now_callback = foo;
+
+  function show() {
+    var c = document.getElementById("build-now-container");
+    if (c) {
+      c.style.display = "block";
+      return true;
+    }
+    return false;
+  }
+
+  // Run immediately in case the element is already there
+  show();
+
+  // Always observe the document for changes (e.g. AJAX updates replacing the sidepanel)
+  var observer = new MutationObserver(show);
+  observer.observe(document, { childList: true, subtree: true });
+
+  // Also listen for DOMContentLoaded as a fallback
+  if (document.readyState === "loading") {
+    document.addEventListener("DOMContentLoaded", show);
+  }
 })();