JS: Handle .js import of .ts file

Author: asger-semmle

javascript/ql/src/semmle/javascript/Modules.qll

@@ -83,9 +83,13 @@ abstract class Module extends TopLevel {
         result = c.(Folder).getJavaScriptFile("index")
       )
       or
-      // handle the case where the import path is missing an extension
+      // handle the case where the import path is missing the extension
       exists(Folder f | f = path.resolveUpTo(path.getNumComponent() - 1) |
         result = f.getJavaScriptFile(path.getBaseName())
+        or
+        // If a js file was not found look for a file that compiles to js
+        not exists(f.getJavaScriptFile(path.getBaseName())) and
+        result = f.getJavaScriptFile(path.getStem())
       )
     )
   }

javascript/ql/src/semmle/javascript/Paths.qll

@@ -205,6 +205,9 @@ abstract class PathExpr extends PathExprBase {
   /** Gets the base name of the folder or file this path refers to. */
   string getBaseName() { result = getValue().(PathString).getBaseName() }
 
+  /** Gets the stem, that is, base name without extension, of the folder or file this path refers to. */
+  string getStem() { result = getValue().(PathString).getStem() }
+
   /**
    * Gets the file or folder that the first `n` components of this path refer to
    * when resolved relative to the root folder of the given `priority`.