Custom at() function in webapp for backwards compatibility

webapp/src/components/labThingsComponents/actionButton.vue

@@ -171,6 +171,25 @@ export default {
   },
 
   mounted() {
+    //Define .at() as a custom function, for backwards compatibility with Connect
+    function at(n) {
+      // ToInteger() abstract op
+      n = Math.trunc(n) || 0;
+      // Allow negative indexing from the end
+      if (n < 0) n += this.length;
+      // OOB access is guaranteed to return undefined
+      if (n < 0 || n >= this.length) return undefined;
+      // Otherwise, this is just normal property access
+      return this[n];
+    }
+  const TypedArray = Reflect.getPrototypeOf(Int8Array);
+  for (const C of [Array, String, TypedArray]) {
+      Object.defineProperty(C.prototype, "at",
+        { value: at,
+          writable: true,
+          enumerable: false,
+          configurable: true });
+    }
     // Check for already running tasks
     if (this.taskStarted != true) {
       this.checkExistingTasks();