Fix error handling in ajax() function

[vchess.git] / client / src / utils / ajax.js

diff --git a/client/src/utils/ajax.js b/client/src/utils/ajax.js
index c0ebbff..83b045c 100644 (file)
--- a/client/src/utils/ajax.js
+++ b/client/src/utils/ajax.js
@@ -1,5 +1,8 @@
 import params from "../parameters"; //for server URL
 
+// TODO: replace by fetch API ?
+// https://www.sitepoint.com/xmlhttprequest-vs-the-fetch-api-whats-best-for-ajax-in-2019/
+
 // From JSON (encoded string values!) to "arg1=...&arg2=..."
 function toQueryString(data)
 {
@@ -14,15 +17,16 @@ function toQueryString(data)
 export function ajax(url, method, data, success, error)
 {
        let xhr = new XMLHttpRequest();
-       if (typeof(data) === "function") //no data
+       if (data === undefined || typeof(data) === "function") //no data
        {
                error = success;
                success = data;
                data = {};
        }
+  if (!success)
+    success = () => {}; //by default, do nothing
        if (!error)
                error = errmsg => { alert(errmsg); };
-
        xhr.onreadystatechange = function() {
                if (this.readyState == 4 && this.status == 200)
                {
@@ -33,10 +37,15 @@ export function ajax(url, method, data, success, error)
                                // Plain text (e.g. for rules retrieval)
                                return success(xhr.responseText);
       }
-      if (!res_json.errmsg)
+      if (!res_json.errmsg && !res_json.errno)
         success(res_json);
                        else
-                               error(res_json.errmsg);
+      {
+        if (!!res_json.errmsg)
+                                 error(res_json.errmsg);
+        else
+          error(res_json.code + ". errno = " + res_json.errno);
+      }
                }
        };