Dont load JavaScript if types packages are present

src/compiler/program.ts

@@ -779,13 +779,18 @@ namespace ts {
         while (true) {
             const baseName = getBaseFileName(directory);
             if (baseName !== "node_modules") {
-                const result =
-                    // first: try to load module as-is
-                    loadModuleFromNodeModulesFolder(moduleName, directory, failedLookupLocations, state) ||
-                    // second: try to load module from the scope '@types'
-                    loadModuleFromNodeModulesFolder(combinePaths("@types", moduleName), directory, failedLookupLocations, state);
-                if (result) {
-                    return result;
+                // Try to load source from the package
+                const packageResult = loadModuleFromNodeModulesFolder(moduleName, directory, failedLookupLocations, state);
+                if (packageResult && hasTypeScriptFileExtension(packageResult)) {
+                    // Always prefer a TypeScript (.ts, .tsx, .d.ts) file shipped with the package
+                    return packageResult;
+                }
+                else {
+                    // Else prefer a types package over non-TypeScript results (e.g. JavaScript files)
+                    const typesResult = loadModuleFromNodeModulesFolder(combinePaths("@types", moduleName), directory, failedLookupLocations, state);
+                    if (typesResult || packageResult) {
+                        return typesResult || packageResult;
+                    }
                 }
             }
 

tests/baselines/reference/project/nodeModulesMaxDepthIncreased/amd/maxDepthIncreased/root.js

@@ -1,6 +1,8 @@
-define(["require", "exports", "m1"], function (require, exports, m1) {
+define(["require", "exports", "m1", "m4"], function (require, exports, m1, m4) {
     "use strict";
     m1.f1("test");
     m1.f2.a = 10;
-    m1.f2.person.age = "10"; // Error: Should be number
+    m1.f2.person.age = "10"; // Should error if loaded the .js files correctly
+    var r1 = m4.test.charAt(2); // Should error if correctly not using the .js file but using @types info
+    var r2 = 3 + m4.foo; // Should be OK if correctly using the @types .d.ts file
 });

tests/baselines/reference/project/nodeModulesMaxDepthIncreased/amd/nodeModulesMaxDepthIncreased.errors.txt

@@ -1,4 +1,5 @@
-maxDepthIncreased/root.ts(4,1): error TS2322: Type 'string' is not assignable to type 'number'.
+maxDepthIncreased/root.ts(7,1): error TS2322: Type 'string' is not assignable to type 'number'.
+maxDepthIncreased/root.ts(8,13): error TS2339: Property 'test' does not exist on type 'typeof "C:/src/TypeScript/tests/cases/projects/NodeModulesSearch/maxDepthIncreased/node_modules/@...'.
 
 
 ==== index.js (0 errors) ====
@@ -28,11 +29,22 @@ maxDepthIncreased/root.ts(4,1): error TS2322: Type 'string' is not assignable to
     
     exports.f2 = m2;
     
-==== maxDepthIncreased/root.ts (1 errors) ====
+==== entry.d.ts (0 errors) ====
+    export declare var foo: number;
+    
+==== maxDepthIncreased/root.ts (2 errors) ====
     import * as m1 from "m1";
+    import * as m4 from "m4";
+    
     m1.f1("test");
     m1.f2.a = 10;
-    m1.f2.person.age = "10"; // Error: Should be number
+    
+    m1.f2.person.age = "10";    // Should error if loaded the .js files correctly
     ~~~~~~~~~~~~~~~~
 !!! error TS2322: Type 'string' is not assignable to type 'number'.
+    let r1 = m4.test.charAt(2); // Should error if correctly not using the .js file but using @types info
+                ~~~~
+!!! error TS2339: Property 'test' does not exist on type 'typeof "C:/src/TypeScript/tests/cases/projects/NodeModulesSearch/maxDepthIncreased/node_modules/@...'.
+    
+    let r2 = 3 + m4.foo; // Should be OK if correctly using the @types .d.ts file
     

tests/baselines/reference/project/nodeModulesMaxDepthIncreased/amd/nodeModulesMaxDepthIncreased.json

@@ -10,6 +10,7 @@
         "maxDepthIncreased/node_modules/m2/node_modules/m3/index.js",
         "maxDepthIncreased/node_modules/m2/entry.js",
         "maxDepthIncreased/node_modules/m1/index.js",
+        "maxDepthIncreased/node_modules/@types/m4/entry.d.ts",
         "maxDepthIncreased/root.ts"
     ],
     "emittedFiles": [

tests/baselines/reference/project/nodeModulesMaxDepthIncreased/node/maxDepthIncreased/root.js

@@ -1,5 +1,8 @@
 "use strict";
 var m1 = require("m1");
+var m4 = require("m4");
 m1.f1("test");
 m1.f2.a = 10;
-m1.f2.person.age = "10"; // Error: Should be number
+m1.f2.person.age = "10"; // Should error if loaded the .js files correctly
+var r1 = m4.test.charAt(2); // Should error if correctly not using the .js file but using @types info
+var r2 = 3 + m4.foo; // Should be OK if correctly using the @types .d.ts file

tests/baselines/reference/project/nodeModulesMaxDepthIncreased/node/nodeModulesMaxDepthIncreased.errors.txt

@@ -1,4 +1,5 @@
-maxDepthIncreased/root.ts(4,1): error TS2322: Type 'string' is not assignable to type 'number'.
+maxDepthIncreased/root.ts(7,1): error TS2322: Type 'string' is not assignable to type 'number'.
+maxDepthIncreased/root.ts(8,13): error TS2339: Property 'test' does not exist on type 'typeof "C:/src/TypeScript/tests/cases/projects/NodeModulesSearch/maxDepthIncreased/node_modules/@...'.
 
 
 ==== index.js (0 errors) ====
@@ -28,11 +29,22 @@ maxDepthIncreased/root.ts(4,1): error TS2322: Type 'string' is not assignable to
     
     exports.f2 = m2;
     
-==== maxDepthIncreased/root.ts (1 errors) ====
+==== entry.d.ts (0 errors) ====
+    export declare var foo: number;
+    
+==== maxDepthIncreased/root.ts (2 errors) ====
     import * as m1 from "m1";
+    import * as m4 from "m4";
+    
     m1.f1("test");
     m1.f2.a = 10;
-    m1.f2.person.age = "10"; // Error: Should be number
+    
+    m1.f2.person.age = "10";    // Should error if loaded the .js files correctly
     ~~~~~~~~~~~~~~~~
 !!! error TS2322: Type 'string' is not assignable to type 'number'.
+    let r1 = m4.test.charAt(2); // Should error if correctly not using the .js file but using @types info
+                ~~~~
+!!! error TS2339: Property 'test' does not exist on type 'typeof "C:/src/TypeScript/tests/cases/projects/NodeModulesSearch/maxDepthIncreased/node_modules/@...'.
+    
+    let r2 = 3 + m4.foo; // Should be OK if correctly using the @types .d.ts file
     

tests/baselines/reference/project/nodeModulesMaxDepthIncreased/node/nodeModulesMaxDepthIncreased.json

@@ -10,6 +10,7 @@
         "maxDepthIncreased/node_modules/m2/node_modules/m3/index.js",
         "maxDepthIncreased/node_modules/m2/entry.js",
         "maxDepthIncreased/node_modules/m1/index.js",
+        "maxDepthIncreased/node_modules/@types/m4/entry.d.ts",
         "maxDepthIncreased/root.ts"
     ],
     "emittedFiles": [

tests/cases/projects/NodeModulesSearch/maxDepthIncreased/node_modules/@types/m4/entry.d.ts

@@ -0,0 +1 @@
+export declare var foo: number;

tests/cases/projects/NodeModulesSearch/maxDepthIncreased/node_modules/@types/m4/package.json

@@ -0,0 +1,5 @@
+{
+  "types": "entry.d.ts",
+  "name": "m4",
+  "version": "1.0.0"
+}

tests/cases/projects/NodeModulesSearch/maxDepthIncreased/node_modules/m4/entry.js

@@ -0,0 +1 @@
+exports.test = "hello, world";

tests/cases/projects/NodeModulesSearch/maxDepthIncreased/node_modules/m4/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "m4",
+  "version": "1.0.0",
+  "main": "entry.js"
+}

tests/cases/projects/NodeModulesSearch/maxDepthIncreased/root.ts

@@ -1,4 +1,10 @@
 import * as m1 from "m1";
+import * as m4 from "m4";
+
 m1.f1("test");
 m1.f2.a = 10;
-m1.f2.person.age = "10"; // Error: Should be number
+
+m1.f2.person.age = "10";    // Should error if loaded the .js files correctly
+let r1 = m4.test.charAt(2); // Should error if correctly not using the .js file but using @types info
+
+let r2 = 3 + m4.foo; // Should be OK if correctly using the @types .d.ts file