Separate client and server codes. Keep everything in one git repo for simplicity

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

diff --git a/client/src/utils/ajax.js b/client/src/utils/ajax.js
new file mode 100644 (file)
index 0000000..065f382
--- /dev/null
+++ b/client/src/utils/ajax.js
@@ -0,0 +1,54 @@
+// From JSON (encoded string values!) to "arg1=...&arg2=..."
+function toQueryString(data)
+{
+       let data_str = "";
+       Object.keys(data).forEach(k => {
+               data_str += k + "=" + encodeURIComponent(data[k]) + "&";
+       });
+       return data_str.slice(0, -1); //remove last "&"
+}
+
+// data, error: optional
+export function ajax(url, method, data, success, error)
+{
+       let xhr = new XMLHttpRequest();
+       if (typeof(data) === "function") //no data
+       {
+               error = success;
+               success = data;
+               data = {};
+       }
+       if (!error)
+               error = errmsg => { alert(errmsg); };
+
+       xhr.onreadystatechange = function() {
+               if (this.readyState == 4 && this.status == 200)
+               {
+                       try {
+                               let res_json = JSON.parse(xhr.responseText);
+                               if (!res_json.errmsg)
+                                       success(res_json);
+                               else
+                                       error(res_json.errmsg);
+                       } catch (e) {
+                               // Plain text (e.g. for rules retrieval)
+                               success(xhr.responseText);
+                       }
+               }
+       };
+
+       if (["GET","DELETE"].includes(method) && !!data)
+       {
+               // Append query params to URL
+               url += "/?" + toQueryString(data);
+       }
+       xhr.open(method, url, true);
+       xhr.setRequestHeader('X-Requested-With', "XMLHttpRequest");
+       if (["POST","PUT"].includes(method))
+       {
+               xhr.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
+               xhr.send(JSON.stringify(data));
+       }
+       else
+               xhr.send();
+}