allow setting no-cors in ping service

Signed-off-by: Jayadeep KM <kmjayadeep@gmail.com>

docs/customservices.md

@@ -144,6 +144,8 @@ For Ping you need to set the type to Ping and provide a url. By default the HEAD
   method: "head"
 ```
 
+You can also specify an optional field `mode` as `no-cors` to allow cross-origin requests from the browser. Setting this field will show the status of the service as `online` if the request is successful, irrespective of the response status code. Check the official [documentation](https://developer.mozilla.org/en-US/docs/Web/API/Request/mode) for more information about this field.
+
 ## Prometheus
 
 For Prometheus you need to set the type to Prometheus and provide a url.

src/components/services/Ping.vue

@@ -39,7 +39,9 @@ export default {
         return;
       }
 
-      this.fetch("/", { method, cache: "no-cache" }, false)
+      const mode = typeof this.item.mode  === "string" ? this.item.mode : "cors";
+
+      this.fetch("/", { method, cache: "no-cache", mode }, false)
         .then(() => {
           this.status = "online";
         })

src/mixins/service.js

@@ -38,6 +38,11 @@ export default {
       }
 
       return fetch(url, options).then((response) => {
+        if (response.type == "opaque") {
+          // For no-cors requests, return empty response
+          return ""
+        }
+
         if (!response.ok) {
           throw new Error("Not 2xx response");
         }