use enum

lib/languages.js

@@ -1,22 +1,29 @@
 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
 // All the languages supported by CodeQL
-exports.ALL_LANGUAGES = ['csharp', 'cpp', 'go', 'java', 'javascript', 'python'];
+var Language;
+(function (Language) {
+    Language["csharp"] = "csharp";
+    Language["cpp"] = "cpp";
+    Language["go"] = "go";
+    Language["java"] = "java";
+    Language["javascript"] = "javascript";
+    Language["python"] = "python";
+})(Language = exports.Language || (exports.Language = {}));
 // Additional names for languages
 const LANGUAGE_ALIASES = {
-    'c': 'cpp',
-    'c++': 'cpp',
-    'c#': 'csharp',
-    'typescript': 'javascript',
+    'c': Language.cpp,
+    'c++': Language.cpp,
+    'c#': Language.csharp,
+    'typescript': Language.javascript,
 };
 // Translate from user input or GitHub's API names for languages to CodeQL's names for languages
 function parseLanguage(language) {
     // Normalise to lower case
     language = language.toLowerCase();
     // See if it's an exact match
-    const parsedLanguage = exports.ALL_LANGUAGES.find(l => l === language);
-    if (parsedLanguage !== undefined) {
-        return parsedLanguage;
+    if (language in Language) {
+        return language;
     }
     // Check language aliases
     if (language in LANGUAGE_ALIASES) {