JavaScript: Introduce convenience predicate for working with typed API-graph nodes.

Author: Max Schaefer

javascript/ql/src/semmle/javascript/ApiGraphs.qll

@@ -286,6 +286,17 @@ module API {
   /** Gets a node corresponding to an export of module `m`. */
   Node moduleExport(string m) { result = Impl::MkModuleDef(m).(Node).getMember("exports") }
 
+  /** Provides helper predicates for accessing API-graph nodes. */
+  module Node {
+    /** Gets a node whose type has the given qualified name. */
+    Node ofType(string moduleName, string exportedName) {
+      exists(TypeName tn |
+        tn.hasQualifiedName(moduleName, exportedName) and
+        result = Impl::MkCanonicalNameUse(tn).(Node).getInstance()
+      )
+    }
+  }
+
   /**
    * An API entry point.
    *

javascript/ql/test/ApiGraphs/typed/NodeOfType.expected

@@ -0,0 +1,3 @@
+| mongodb | Collection | index.ts:14:3:14:17 | getCollection() |
+| mongoose | Model | index.ts:22:3:22:20 | getMongooseModel() |
+| mongoose | Query | index.ts:23:3:23:20 | getMongooseQuery() |

javascript/ql/test/ApiGraphs/typed/NodeOfType.ql

@@ -0,0 +1,4 @@
+import javascript
+
+from string mod, string tp
+select mod, tp, API::Node::ofType(mod, tp).getAnImmediateUse()