feat: add reusable announceToScreenReader helper and update block.js

Author: abhnish

js/utils/utils.js

@@ -38,7 +38,7 @@ if (typeof module !== "undefined" && module.exports) {
 }
 
 /* exported
-   canvasPixelRatio, changeImage, closeBlkWidgets, closeWidgets,
+   announceToScreenReader,canvasPixelRatio, changeImage, closeBlkWidgets, closeWidgets,
    delayExecution, displayMsg, doBrowserCheck, docByClass, docByName,
    docBySelector, docByTagName, doPublish, doStopVideoCam, doSVG,
    doUseCamera, format, getTextWidth, hideDOMLabel, httpGet, httpPost, HttpRequest,
@@ -1456,6 +1456,25 @@ let closeBlkWidgets = name => {
  * @param {*[]} viewArgs - Constructor arguments for the view.
  * @returns {void}
  */
+/**
+ * Announces a message to screen readers via a shared aria-live region.
+ * Creates the region lazily on first use and reuses it for all subsequent calls.
+ * @param {string} msg - The message to announce.
+ */
+const announceToScreenReader = msg => {
+    let region = document.getElementById("mbA11yLiveRegion");
+    if (!region) {
+        region = document.createElement("div");
+        region.id = "mbA11yLiveRegion";
+        region.setAttribute("role", "status");
+        region.setAttribute("aria-live", "polite");
+        region.setAttribute("aria-atomic", "true");
+        region.style.cssText =
+            "position:absolute;left:-9999px;width:1px;height:1px;overflow:hidden;";
+        document.body.appendChild(region);
+    }
+    region.textContent = msg;
+};
 let importMembers = (obj, className, modelArgs, viewArgs) => {
     /**
      * Adds methods and variables of one class to another class's instance.
@@ -1544,6 +1563,7 @@ if (typeof module !== "undefined" && module.exports) {
         processPluginData,
         processMacroData,
         hideDOMLabel,
-        displayMsg
+        displayMsg,
+        announceToScreenReader
     };
 }