diff --git a/lib/tsc.js b/lib/tsc.js
index be8721336d0d3..43f150dd77aec 100644
--- a/lib/tsc.js
+++ b/lib/tsc.js
@@ -142,7 +142,7 @@ var ts;
 })(ts || (ts = {}));
 var ts;
 (function (ts) {
-    ts.version = "2.3.4";
+    ts.version = "2.3.5";
 })(ts || (ts = {}));
 (function (ts) {
     ts.collator = typeof Intl === "object" && typeof Intl.Collator === "function" ? new Intl.Collator(undefined, { usage: "sort", sensitivity: "accent" }) : undefined;
@@ -53897,9 +53897,9 @@ var ts;
                 }
                 var typeChecker = getDiagnosticsProducingTypeChecker();
                 ts.Debug.assert(!!sourceFile.bindDiagnostics);
-                var bindDiagnostics = sourceFile.bindDiagnostics;
-                var includeCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
-                var checkDiagnostics = includeCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : [];
+                var includeBindAndCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
+                var bindDiagnostics = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
+                var checkDiagnostics = includeBindAndCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : emptyArray;
                 var fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 var programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
                 var diagnostics = bindDiagnostics.concat(checkDiagnostics, fileProcessingDiagnosticsInFile, programDiagnosticsInFile);
diff --git a/lib/tsserver.js b/lib/tsserver.js
index 19241091ec7ce..0e654529be88e 100644
--- a/lib/tsserver.js
+++ b/lib/tsserver.js
@@ -1106,7 +1106,7 @@ var ts;
 })(ts || (ts = {}));
 var ts;
 (function (ts) {
-    ts.version = "2.3.4";
+    ts.version = "2.3.5";
 })(ts || (ts = {}));
 (function (ts) {
     var Ternary;
@@ -55281,9 +55281,9 @@ var ts;
                 }
                 var typeChecker = getDiagnosticsProducingTypeChecker();
                 ts.Debug.assert(!!sourceFile.bindDiagnostics);
-                var bindDiagnostics = sourceFile.bindDiagnostics;
-                var includeCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
-                var checkDiagnostics = includeCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : [];
+                var includeBindAndCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
+                var bindDiagnostics = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
+                var checkDiagnostics = includeBindAndCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : emptyArray;
                 var fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 var programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
                 var diagnostics = bindDiagnostics.concat(checkDiagnostics, fileProcessingDiagnosticsInFile, programDiagnosticsInFile);
diff --git a/lib/tsserverlibrary.d.ts b/lib/tsserverlibrary.d.ts
index b6738def57e52..d6de1acd35a7b 100644
--- a/lib/tsserverlibrary.d.ts
+++ b/lib/tsserverlibrary.d.ts
@@ -2275,7 +2275,7 @@ declare namespace ts {
     }
 }
 declare namespace ts {
-    const version = "2.3.4";
+    const version = "2.3.5";
 }
 declare function setTimeout(handler: (...args: any[]) => void, timeout: number): any;
 declare function clearTimeout(handle: any): void;
diff --git a/lib/tsserverlibrary.js b/lib/tsserverlibrary.js
index 2a052751651ae..0aecf56ca7009 100644
--- a/lib/tsserverlibrary.js
+++ b/lib/tsserverlibrary.js
@@ -1106,7 +1106,7 @@ var ts;
 })(ts || (ts = {}));
 var ts;
 (function (ts) {
-    ts.version = "2.3.4";
+    ts.version = "2.3.5";
 })(ts || (ts = {}));
 (function (ts) {
     var Ternary;
@@ -56665,9 +56665,9 @@ var ts;
                 }
                 var typeChecker = getDiagnosticsProducingTypeChecker();
                 ts.Debug.assert(!!sourceFile.bindDiagnostics);
-                var bindDiagnostics = sourceFile.bindDiagnostics;
-                var includeCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
-                var checkDiagnostics = includeCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : [];
+                var includeBindAndCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
+                var bindDiagnostics = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
+                var checkDiagnostics = includeBindAndCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : emptyArray;
                 var fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 var programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
                 var diagnostics = bindDiagnostics.concat(checkDiagnostics, fileProcessingDiagnosticsInFile, programDiagnosticsInFile);
diff --git a/lib/typescript.d.ts b/lib/typescript.d.ts
index 2148a040d3374..8e5d693129f99 100644
--- a/lib/typescript.d.ts
+++ b/lib/typescript.d.ts
@@ -2519,7 +2519,7 @@ declare namespace ts {
 }
 declare namespace ts {
     /** The version of the TypeScript compiler release */
-    const version = "2.3.4";
+    const version = "2.3.5";
 }
 declare function setTimeout(handler: (...args: any[]) => void, timeout: number): any;
 declare function clearTimeout(handle: any): void;
diff --git a/lib/typescript.js b/lib/typescript.js
index d2840acde85db..f652fbabfc9d9 100644
--- a/lib/typescript.js
+++ b/lib/typescript.js
@@ -1262,7 +1262,7 @@ var ts;
 var ts;
 (function (ts) {
     /** The version of the TypeScript compiler release */
-    ts.version = "2.3.4";
+    ts.version = "2.3.5";
 })(ts || (ts = {}));
 /* @internal */
 (function (ts) {
@@ -67476,10 +67476,10 @@ var ts;
                 }
                 var typeChecker = getDiagnosticsProducingTypeChecker();
                 ts.Debug.assert(!!sourceFile.bindDiagnostics);
-                var bindDiagnostics = sourceFile.bindDiagnostics;
                 // For JavaScript files, we don't want to report semantic errors unless explicitly requested.
-                var includeCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
-                var checkDiagnostics = includeCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : [];
+                var includeBindAndCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
+                var bindDiagnostics = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
+                var checkDiagnostics = includeBindAndCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : emptyArray;
                 var fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 var programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
                 var diagnostics = bindDiagnostics.concat(checkDiagnostics, fileProcessingDiagnosticsInFile, programDiagnosticsInFile);
diff --git a/lib/typescriptServices.d.ts b/lib/typescriptServices.d.ts
index 25345e1f5b65f..ef1da64857e79 100644
--- a/lib/typescriptServices.d.ts
+++ b/lib/typescriptServices.d.ts
@@ -2519,7 +2519,7 @@ declare namespace ts {
 }
 declare namespace ts {
     /** The version of the TypeScript compiler release */
-    const version = "2.3.4";
+    const version = "2.3.5";
 }
 declare function setTimeout(handler: (...args: any[]) => void, timeout: number): any;
 declare function clearTimeout(handle: any): void;
diff --git a/lib/typescriptServices.js b/lib/typescriptServices.js
index d2840acde85db..f652fbabfc9d9 100644
--- a/lib/typescriptServices.js
+++ b/lib/typescriptServices.js
@@ -1262,7 +1262,7 @@ var ts;
 var ts;
 (function (ts) {
     /** The version of the TypeScript compiler release */
-    ts.version = "2.3.4";
+    ts.version = "2.3.5";
 })(ts || (ts = {}));
 /* @internal */
 (function (ts) {
@@ -67476,10 +67476,10 @@ var ts;
                 }
                 var typeChecker = getDiagnosticsProducingTypeChecker();
                 ts.Debug.assert(!!sourceFile.bindDiagnostics);
-                var bindDiagnostics = sourceFile.bindDiagnostics;
                 // For JavaScript files, we don't want to report semantic errors unless explicitly requested.
-                var includeCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
-                var checkDiagnostics = includeCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : [];
+                var includeBindAndCheckDiagnostics = !ts.isSourceFileJavaScript(sourceFile) || ts.isCheckJsEnabledForFile(sourceFile, options);
+                var bindDiagnostics = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
+                var checkDiagnostics = includeBindAndCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : emptyArray;
                 var fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 var programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
                 var diagnostics = bindDiagnostics.concat(checkDiagnostics, fileProcessingDiagnosticsInFile, programDiagnosticsInFile);
diff --git a/lib/typingsInstaller.js b/lib/typingsInstaller.js
index cc60f08af6e01..f1d365b15e76d 100644
--- a/lib/typingsInstaller.js
+++ b/lib/typingsInstaller.js
@@ -152,7 +152,7 @@ var ts;
 })(ts || (ts = {}));
 var ts;
 (function (ts) {
-    ts.version = "2.3.4";
+    ts.version = "2.3.5";
 })(ts || (ts = {}));
 (function (ts) {
     ts.collator = typeof Intl === "object" && typeof Intl.Collator === "function" ? new Intl.Collator(undefined, { usage: "sort", sensitivity: "accent" }) : undefined;
diff --git a/package.json b/package.json
index 52531aa024bb5..e5079aa9285d5 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
     "name": "typescript",
     "author": "Microsoft Corp.",
     "homepage": "http://typescriptlang.org/",
-    "version": "2.3.4",
+    "version": "2.3.5",
     "license": "Apache-2.0",
     "description": "TypeScript is a language for application scale JavaScript development",
     "keywords": [
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index d777d4ea71204..1839fdc6aadd9 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -3,7 +3,7 @@
 
 namespace ts {
     /** The version of the TypeScript compiler release */
-    export const version = "2.3.4";
+    export const version = "2.3.5";
 }
 
 /* @internal */
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 347e6e97ebd81..5d563d455155d 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -918,10 +918,10 @@ namespace ts {
                 const typeChecker = getDiagnosticsProducingTypeChecker();
 
                 Debug.assert(!!sourceFile.bindDiagnostics);
-                const bindDiagnostics = sourceFile.bindDiagnostics;
                 // For JavaScript files, we don't want to report semantic errors unless explicitly requested.
-                const includeCheckDiagnostics = !isSourceFileJavaScript(sourceFile) || isCheckJsEnabledForFile(sourceFile, options);
-                const checkDiagnostics = includeCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : [];
+                const includeBindAndCheckDiagnostics = !isSourceFileJavaScript(sourceFile) || isCheckJsEnabledForFile(sourceFile, options);
+                const bindDiagnostics = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
+                const checkDiagnostics = includeBindAndCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : emptyArray;
                 const fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 const programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
 
diff --git a/tests/baselines/reference/jsFileCompilationBindMultipleDefaultExports.errors.txt b/tests/baselines/reference/jsFileCompilationBindMultipleDefaultExports.errors.txt
index 05fecf03d3069..9a9a7a12db9ca 100644
--- a/tests/baselines/reference/jsFileCompilationBindMultipleDefaultExports.errors.txt
+++ b/tests/baselines/reference/jsFileCompilationBindMultipleDefaultExports.errors.txt
@@ -1,15 +1,21 @@
 tests/cases/compiler/a.js(1,22): error TS2528: A module cannot have multiple default exports.
+tests/cases/compiler/a.js(1,22): error TS2652: Merged declaration 'a' cannot include a default export declaration. Consider adding a separate 'export default a' declaration instead.
 tests/cases/compiler/a.js(3,1): error TS2528: A module cannot have multiple default exports.
 tests/cases/compiler/a.js(3,16): error TS1109: Expression expected.
+tests/cases/compiler/a.js(3,20): error TS2652: Merged declaration 'a' cannot include a default export declaration. Consider adding a separate 'export default a' declaration instead.
 
 
-==== tests/cases/compiler/a.js (3 errors) ====
+==== tests/cases/compiler/a.js (5 errors) ====
     export default class a {
                          ~
 !!! error TS2528: A module cannot have multiple default exports.
+                         ~
+!!! error TS2652: Merged declaration 'a' cannot include a default export declaration. Consider adding a separate 'export default a' declaration instead.
     }
     export default var a = 10;
     ~~~~~~~~~~~~~~
 !!! error TS2528: A module cannot have multiple default exports.
                    ~~~
-!!! error TS1109: Expression expected.
\ No newline at end of file
+!!! error TS1109: Expression expected.
+                       ~
+!!! error TS2652: Merged declaration 'a' cannot include a default export declaration. Consider adding a separate 'export default a' declaration instead.
\ No newline at end of file
diff --git a/tests/baselines/reference/jsFileCompilationBindStrictModeErrors.errors.txt b/tests/baselines/reference/jsFileCompilationBindStrictModeErrors.errors.txt
index d681cec3775b0..ed19b5c4a9b89 100644
--- a/tests/baselines/reference/jsFileCompilationBindStrictModeErrors.errors.txt
+++ b/tests/baselines/reference/jsFileCompilationBindStrictModeErrors.errors.txt
@@ -1,9 +1,12 @@
 tests/cases/compiler/a.js(5,5): error TS1117: An object literal cannot have multiple properties with the same name in strict mode.
+tests/cases/compiler/a.js(5,5): error TS2300: Duplicate identifier 'a'.
 tests/cases/compiler/a.js(7,5): error TS1212: Identifier expected. 'let' is a reserved word in strict mode.
 tests/cases/compiler/a.js(8,8): error TS1102: 'delete' cannot be called on an identifier in strict mode.
+tests/cases/compiler/a.js(8,8): error TS2703: The operand of a delete operator must be a property reference.
 tests/cases/compiler/a.js(10,10): error TS1100: Invalid use of 'eval' in strict mode.
 tests/cases/compiler/a.js(12,10): error TS1100: Invalid use of 'arguments' in strict mode.
 tests/cases/compiler/a.js(15,1): error TS1101: 'with' statements are not allowed in strict mode.
+tests/cases/compiler/a.js(15,1): error TS2410: The 'with' statement is not supported. All symbols in a 'with' block will have type 'any'.
 tests/cases/compiler/b.js(3,7): error TS1210: Invalid use of 'eval'. Class definitions are automatically in strict mode.
 tests/cases/compiler/b.js(6,13): error TS1213: Identifier expected. 'let' is a reserved word in strict mode. Class definitions are automatically in strict mode.
 tests/cases/compiler/c.js(1,12): error TS1214: Identifier expected. 'let' is a reserved word in strict mode. Modules are automatically in strict mode.
@@ -12,7 +15,7 @@ tests/cases/compiler/d.js(2,9): error TS1121: Octal literals are not allowed in
 tests/cases/compiler/d.js(2,11): error TS1005: ',' expected.
 
 
-==== tests/cases/compiler/a.js (6 errors) ====
+==== tests/cases/compiler/a.js (9 errors) ====
     "use strict";
     var a = {
         a: "hello", // error
@@ -20,6 +23,8 @@ tests/cases/compiler/d.js(2,11): error TS1005: ',' expected.
         a: 10 // error
         ~
 !!! error TS1117: An object literal cannot have multiple properties with the same name in strict mode.
+        ~
+!!! error TS2300: Duplicate identifier 'a'.
     };
     var let = 10; // error
         ~~~
@@ -27,6 +32,8 @@ tests/cases/compiler/d.js(2,11): error TS1005: ',' expected.
     delete a; // error
            ~
 !!! error TS1102: 'delete' cannot be called on an identifier in strict mode.
+           ~
+!!! error TS2703: The operand of a delete operator must be a property reference.
     try {
     } catch (eval) { // error
              ~~~~
@@ -40,6 +47,8 @@ tests/cases/compiler/d.js(2,11): error TS1005: ',' expected.
     with (a) {
     ~~~~
 !!! error TS1101: 'with' statements are not allowed in strict mode.
+    ~~~~~~~~
+!!! error TS2410: The 'with' statement is not supported. All symbols in a 'with' block will have type 'any'.
         b = 10;
     }
     
diff --git a/tests/baselines/reference/unreachableJavascriptChecked.errors.txt b/tests/baselines/reference/unreachableJavascriptChecked.errors.txt
new file mode 100644
index 0000000000000..c66b342177fcd
--- /dev/null
+++ b/tests/baselines/reference/unreachableJavascriptChecked.errors.txt
@@ -0,0 +1,10 @@
+tests/cases/compiler/unreachable.js(3,5): error TS7027: Unreachable code detected.
+
+
+==== tests/cases/compiler/unreachable.js (1 errors) ====
+    function unreachable() {
+        return 1;
+        return 2;
+        ~~~~~~
+!!! error TS7027: Unreachable code detected.
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/unreachableJavascriptChecked.js b/tests/baselines/reference/unreachableJavascriptChecked.js
new file mode 100644
index 0000000000000..6bf264bf3d22c
--- /dev/null
+++ b/tests/baselines/reference/unreachableJavascriptChecked.js
@@ -0,0 +1,11 @@
+//// [unreachable.js]
+function unreachable() {
+    return 1;
+    return 2;
+}
+
+//// [unreachable.js]
+function unreachable() {
+    return 1;
+    return 2;
+}
diff --git a/tests/baselines/reference/unreachableJavascriptUnchecked.js b/tests/baselines/reference/unreachableJavascriptUnchecked.js
new file mode 100644
index 0000000000000..6bf264bf3d22c
--- /dev/null
+++ b/tests/baselines/reference/unreachableJavascriptUnchecked.js
@@ -0,0 +1,11 @@
+//// [unreachable.js]
+function unreachable() {
+    return 1;
+    return 2;
+}
+
+//// [unreachable.js]
+function unreachable() {
+    return 1;
+    return 2;
+}
diff --git a/tests/baselines/reference/unreachableJavascriptUnchecked.symbols b/tests/baselines/reference/unreachableJavascriptUnchecked.symbols
new file mode 100644
index 0000000000000..f2db6a6a3477f
--- /dev/null
+++ b/tests/baselines/reference/unreachableJavascriptUnchecked.symbols
@@ -0,0 +1,7 @@
+=== tests/cases/compiler/unreachable.js ===
+function unreachable() {
+>unreachable : Symbol(unreachable, Decl(unreachable.js, 0, 0))
+
+    return 1;
+    return 2;
+}
diff --git a/tests/baselines/reference/unreachableJavascriptUnchecked.types b/tests/baselines/reference/unreachableJavascriptUnchecked.types
new file mode 100644
index 0000000000000..266a9038875cb
--- /dev/null
+++ b/tests/baselines/reference/unreachableJavascriptUnchecked.types
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/unreachable.js ===
+function unreachable() {
+>unreachable : () => 1 | 2
+
+    return 1;
+>1 : 1
+
+    return 2;
+>2 : 2
+}
diff --git a/tests/cases/compiler/jsFileCompilationBindDuplicateIdentifier.ts b/tests/cases/compiler/jsFileCompilationBindDuplicateIdentifier.ts
index 3433adc17d54e..7659350d489f9 100644
--- a/tests/cases/compiler/jsFileCompilationBindDuplicateIdentifier.ts
+++ b/tests/cases/compiler/jsFileCompilationBindDuplicateIdentifier.ts
@@ -1,4 +1,5 @@
 // @allowJs: true
+// @checkJs: true
 // @noEmit: true
 // @filename: a.js
 var a = 10;
diff --git a/tests/cases/compiler/jsFileCompilationBindErrors.ts b/tests/cases/compiler/jsFileCompilationBindErrors.ts
index 37bdbc62916a0..7c43b329a4740 100644
--- a/tests/cases/compiler/jsFileCompilationBindErrors.ts
+++ b/tests/cases/compiler/jsFileCompilationBindErrors.ts
@@ -1,4 +1,5 @@
 // @allowJs: true
+// @checkJs: true
 // @noEmit: true
 // @filename: a.js
 let C = "sss";
diff --git a/tests/cases/compiler/jsFileCompilationBindMultipleDefaultExports.ts b/tests/cases/compiler/jsFileCompilationBindMultipleDefaultExports.ts
index 32a9e77fcc765..e7816f92ad109 100644
--- a/tests/cases/compiler/jsFileCompilationBindMultipleDefaultExports.ts
+++ b/tests/cases/compiler/jsFileCompilationBindMultipleDefaultExports.ts
@@ -1,4 +1,5 @@
 // @allowJs: true
+// @checkJs: true
 // @noEmit: true
 // @filename: a.js
 // @target: es6
diff --git a/tests/cases/compiler/jsFileCompilationBindReachabilityErrors.ts b/tests/cases/compiler/jsFileCompilationBindReachabilityErrors.ts
index b95f85c21398c..e92732313163a 100644
--- a/tests/cases/compiler/jsFileCompilationBindReachabilityErrors.ts
+++ b/tests/cases/compiler/jsFileCompilationBindReachabilityErrors.ts
@@ -1,4 +1,5 @@
 // @allowJs: true
+// @checkJs: true
 // @noEmit: true
 // @filename: a.js
 // @noFallthroughCasesInSwitch: true
diff --git a/tests/cases/compiler/jsFileCompilationBindStrictModeErrors.ts b/tests/cases/compiler/jsFileCompilationBindStrictModeErrors.ts
index 30b43b1990e32..527927be6e6f5 100644
--- a/tests/cases/compiler/jsFileCompilationBindStrictModeErrors.ts
+++ b/tests/cases/compiler/jsFileCompilationBindStrictModeErrors.ts
@@ -1,4 +1,5 @@
 // @allowJs: true
+// @checkJs: true
 // @noEmit: true
 // @filename: a.js
 // @target: es6
diff --git a/tests/cases/compiler/unreachableJavascriptChecked.ts b/tests/cases/compiler/unreachableJavascriptChecked.ts
new file mode 100644
index 0000000000000..4db98c4c8c4e1
--- /dev/null
+++ b/tests/cases/compiler/unreachableJavascriptChecked.ts
@@ -0,0 +1,8 @@
+// @Filename: unreachable.js
+// @allowJs: true
+// @checkJs: true
+// @outDir: out
+function unreachable() {
+    return 1;
+    return 2;
+}
\ No newline at end of file
diff --git a/tests/cases/compiler/unreachableJavascriptUnchecked.ts b/tests/cases/compiler/unreachableJavascriptUnchecked.ts
new file mode 100644
index 0000000000000..d5b1f45e28204
--- /dev/null
+++ b/tests/cases/compiler/unreachableJavascriptUnchecked.ts
@@ -0,0 +1,8 @@
+// @Filename: unreachable.js
+// @allowJs: true
+// @checkJs: false
+// @outDir: out
+function unreachable() {
+    return 1;
+    return 2;
+}
\ No newline at end of file