diff --git a/src/printer.js b/src/printer.js
index cf504dfa..9c005ebb 100644
--- a/src/printer.js
+++ b/src/printer.js
@@ -770,7 +770,7 @@ function genericPrintNoParens(path, options, print, args) {
         n.typeParameters ? path.call(print, "typeParameters") : "",
         " "
       );
-      
+
       if (n.heritage.length) {
         parts.push(
           "extends ",
@@ -778,9 +778,9 @@ function genericPrintNoParens(path, options, print, args) {
           " "
         );
       }
-      
+
       parts.push(path.call(print, "body"));
-      
+
       return concat(parts);
     case "ObjectExpression":
     case "ObjectPattern":
@@ -805,7 +805,7 @@ function genericPrintNoParens(path, options, print, args) {
       const parent = path.getParentNode(0);
       const parentIsUnionTypeAnnotation = parent.type === "UnionTypeAnnotation";
       let propertiesField;
-      
+
       if (n.type === 'TSTypeLiteral') {
         propertiesField = "members";
       } else if (n.type === "TSInterfaceBody") {
@@ -1129,8 +1129,7 @@ function genericPrintNoParens(path, options, print, args) {
       parts = [
         isNodeStartingWithDeclare(n, options) ? "declare " : "",
         n.kind,
-        " ",
-        printed[0],
+        printed.length ? concat([" ", printed[0]]) : "",
         indent(concat(printed.slice(1).map(p => concat([",", line, p]))))
       ];
 
@@ -1629,11 +1628,11 @@ function genericPrintNoParens(path, options, print, args) {
       return concat(parts);
     case "TSInterfaceHeritage":
       parts.push(path.call(print, "id"));
-      
+
       if (n.typeParameters) {
         parts.push(path.call(print, "typeParameters"));
       }
-      
+
       return concat(parts);
     case "TSHeritageClause":
       return join(", ", path.map(print, "types"));
@@ -2207,7 +2206,11 @@ function genericPrintNoParens(path, options, print, args) {
         path.call(print, "typeAnnotation")
       ]);
     case "TSFirstTypeNode":
-      return concat([n.parameterName.name, " is ", path.call(print, "typeAnnotation")])
+      return concat([
+        path.call(print, "parameterName"),
+        " is ",
+        path.call(print, "typeAnnotation")
+      ]);
     case "TSNonNullExpression":
       return concat([path.call(print, "expression"), "!"]);
     case "TSThisType":
@@ -2748,7 +2751,7 @@ function printArgumentsList(path, options, print) {
 function printFunctionTypeParameters(path, options, print) {
   const fun = path.getValue();
   const paramsFieldIsArray = Array.isArray(fun["typeParameters"])
-  
+
   if (fun.typeParameters) {
     // for TSFunctionType typeParameters is an array
     // for FunctionTypeAnnotation it's a single node
diff --git a/tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap b/tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap
index 2fd97e68..1b16b7d9 100644
--- a/tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap
@@ -194,6 +194,12 @@ interface i2 {
 
 `;
 
+exports[`downlevelLetConst1.ts 1`] = `
+const~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+const;
+
+`;
+
 exports[`errorOnInitializerInInterfaceProperty.ts 1`] = `
 interface Foo {
     bar: number = 5;
diff --git a/tests/typescript/compiler/downlevelLetConst1.ts b/tests/typescript/compiler/downlevelLetConst1.ts
new file mode 100644
index 00000000..8baacf4e
--- /dev/null
+++ b/tests/typescript/compiler/downlevelLetConst1.ts
@@ -0,0 +1 @@
+const
\ No newline at end of file
diff --git a/tests/typescript/conformance/declarationEmit/typePredicates/__snapshots__/jsfmt.spec.js.snap b/tests/typescript/conformance/declarationEmit/typePredicates/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 00000000..475e25a3
--- /dev/null
+++ b/tests/typescript/conformance/declarationEmit/typePredicates/__snapshots__/jsfmt.spec.js.snap
@@ -0,0 +1,26 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`declarationEmitThisPredicatesWithPrivateName01.ts 1`] = `
+// @declaration: true
+// @module: commonjs
+
+export class C {
+    m(): this is D {
+        return this instanceof D;
+    }
+}
+
+class D extends C {
+}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// @declaration: true
+// @module: commonjs
+
+export class C {
+  m(): this is D {
+    return this instanceof D;
+  }
+}
+
+class D extends C {}
+
+`;
diff --git a/tests/typescript/conformance/declarationEmit/typePredicates/declarationEmitThisPredicatesWithPrivateName01.ts b/tests/typescript/conformance/declarationEmit/typePredicates/declarationEmitThisPredicatesWithPrivateName01.ts
new file mode 100644
index 00000000..461c7d17
--- /dev/null
+++ b/tests/typescript/conformance/declarationEmit/typePredicates/declarationEmitThisPredicatesWithPrivateName01.ts
@@ -0,0 +1,11 @@
+// @declaration: true
+// @module: commonjs
+
+export class C {
+    m(): this is D {
+        return this instanceof D;
+    }
+}
+
+class D extends C {
+}
\ No newline at end of file
diff --git a/tests/typescript/conformance/declarationEmit/typePredicates/jsfmt.spec.js b/tests/typescript/conformance/declarationEmit/typePredicates/jsfmt.spec.js
new file mode 100644
index 00000000..bc085c48
--- /dev/null
+++ b/tests/typescript/conformance/declarationEmit/typePredicates/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(__dirname, { parser: "typescript" });
diff --git a/tests/typescript/conformance/parser/ecmascript5/Statements/__snapshots__/jsfmt.spec.js.snap b/tests/typescript/conformance/parser/ecmascript5/Statements/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 00000000..d0586696
--- /dev/null
+++ b/tests/typescript/conformance/parser/ecmascript5/Statements/__snapshots__/jsfmt.spec.js.snap
@@ -0,0 +1,31 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`parserES5ForOfStatement2.ts 1`] = `
+//@target: ES5
+for (var of X) {
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//@target: ES5
+for (var of X) {
+}
+
+`;
+
+exports[`parserES5ForOfStatement21.ts 1`] = `
+//@target: ES5
+for (var of of) { }
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//@target: ES5
+for (var of of) {
+}
+
+`;
+
+exports[`parserForInStatement2.ts 1`] = `
+for (var in X) {
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+for (var in X) {
+}
+
+`;
diff --git a/tests/typescript/conformance/parser/ecmascript5/Statements/jsfmt.spec.js b/tests/typescript/conformance/parser/ecmascript5/Statements/jsfmt.spec.js
new file mode 100644
index 00000000..bc085c48
--- /dev/null
+++ b/tests/typescript/conformance/parser/ecmascript5/Statements/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(__dirname, { parser: "typescript" });
diff --git a/tests/typescript/conformance/parser/ecmascript5/Statements/parserES5ForOfStatement2.ts b/tests/typescript/conformance/parser/ecmascript5/Statements/parserES5ForOfStatement2.ts
new file mode 100644
index 00000000..d67611bd
--- /dev/null
+++ b/tests/typescript/conformance/parser/ecmascript5/Statements/parserES5ForOfStatement2.ts
@@ -0,0 +1,3 @@
+//@target: ES5
+for (var of X) {
+}
diff --git a/tests/typescript/conformance/parser/ecmascript5/Statements/parserES5ForOfStatement21.ts b/tests/typescript/conformance/parser/ecmascript5/Statements/parserES5ForOfStatement21.ts
new file mode 100644
index 00000000..6d28e4c0
--- /dev/null
+++ b/tests/typescript/conformance/parser/ecmascript5/Statements/parserES5ForOfStatement21.ts
@@ -0,0 +1,2 @@
+//@target: ES5
+for (var of of) { }
diff --git a/tests/typescript/conformance/parser/ecmascript5/Statements/parserForInStatement2.ts b/tests/typescript/conformance/parser/ecmascript5/Statements/parserForInStatement2.ts
new file mode 100644
index 00000000..3bf9bc29
--- /dev/null
+++ b/tests/typescript/conformance/parser/ecmascript5/Statements/parserForInStatement2.ts
@@ -0,0 +1,2 @@
+for (var in X) {
+}