更新前端静态网页获取方式，放弃使用后端获取api

frontend/node_modules/dns-packet/classes.js

@@ -0,0 +1,23 @@
+'use strict'
+
+exports.toString = function (klass) {
+  switch (klass) {
+    case 1: return 'IN'
+    case 2: return 'CS'
+    case 3: return 'CH'
+    case 4: return 'HS'
+    case 255: return 'ANY'
+  }
+  return 'UNKNOWN_' + klass
+}
+
+exports.toClass = function (name) {
+  switch (name.toUpperCase()) {
+    case 'IN': return 1
+    case 'CS': return 2
+    case 'CH': return 3
+    case 'HS': return 4
+    case 'ANY': return 255
+  }
+  return 0
+}