戈mprove the readibility of important condition

server/util.js

@@ -1,6 +1,10 @@
 // Common JS cannot be used in frontend sadly
 // sleep, ucfirst is duplicated in ../src/util-frontend.js
 
+exports.DOWN = 0;
+exports.UP = 1;
+exports.PENDING = 2;
+
 exports.sleep = function (ms) {
     return new Promise(resolve => setTimeout(resolve, ms));
 }