Add base parser

javascript/_baseParser.js

@@ -0,0 +1,14 @@
+class BaseTagParser {
+    triggerCondition = null;
+
+    constructor (triggerCondition) {
+        if (new.target === BaseCompletionParser) {
+            throw new TypeError("Cannot construct abstract BaseCompletionParser directly");
+        }
+        this.triggerCondition = triggerCondition;
+    }
+
+    parse() {
+        throw new NotImplementedError();
+    }
+}