client/src/utils/ajax.js

   1 import params from "../parameters"; //for server URL
   2
   3 // From JSON (encoded string values!) to "arg1=...&arg2=..."
   4 function toQueryString(data)
   5 {
   6     let data_str = "";
   7     Object.keys(data).forEach(k => {
   8         data_str += k + "=" + encodeURIComponent(data[k]) + "&";
   9     });
  10     return data_str.slice(0, -1); //remove last "&"
  11 }
  12
  13 // data, error: optional
  14 export function ajax(url, method, data, success, error)
  15 {
  16     let xhr = new XMLHttpRequest();
  17     if (typeof(data) === "function") //no data
  18     {
  19         error = success;
  20         success = data;
  21         data = {};
  22     }
  23     if (!error)
  24         error = errmsg => { alert(errmsg); };
  25
  26     xhr.onreadystatechange = function() {
  27         if (this.readyState == 4 && this.status == 200)
  28         {
  29       let res_json = "";
  30             try {
  31                 res_json = JSON.parse(xhr.responseText);
  32       } catch (e) {
  33                 // Plain text (e.g. for rules retrieval)
  34                 return success(xhr.responseText);
  35       }
  36       if (!res_json.errmsg)
  37         success(res_json);
  38             else
  39                 error(res_json.errmsg);
  40         }
  41     };
  42
  43     if (["GET","DELETE"].includes(method) && !!data)
  44     {
  45         // Append query params to URL
  46         url += "/?" + toQueryString(data);
  47     }
  48     xhr.open(method, params.serverUrl + url, true);
  49     xhr.setRequestHeader('X-Requested-With', "XMLHttpRequest");
  50     // Next line because logout and authenticate set (cross-domain in dev mode) cookies
  51   if (url.startsWith("/authenticate") || url.startsWith("/logout"))
  52     xhr.withCredentials = true;
  53   if (["POST","PUT"].includes(method))
  54     {
  55         xhr.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
  56         xhr.send(JSON.stringify(data));
  57     }
  58     else
  59         xhr.send();
  60 }