diff --git a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsFor.java b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsFor.java
index d2d97f21ad4..98054847f77 100644
--- a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsFor.java
+++ b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsFor.java
@@ -18,7 +18,7 @@ import org.jetbrains.annotations.NotNull;
  * Note that any of the parts of the <code>for</code> loop header can be
  * <code>null</code>, although the body will never be null.
  */
-public class JsFor extends SourceInfoAwareJsNode implements JsStatement {
+public class JsFor extends SourceInfoAwareJsNode implements JsLoop {
     private JsStatement body;
     private JsExpression condition;
     private JsExpression incrementExpression;
diff --git a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsForIn.java b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsForIn.java
index 5be526bacc4..2ccf7c896fa 100644
--- a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsForIn.java
+++ b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsForIn.java
@@ -7,7 +7,7 @@ package org.jetbrains.kotlin.js.backend.ast;
 import org.jetbrains.kotlin.js.util.AstUtil;
 import org.jetbrains.annotations.NotNull;
 
-public class JsForIn extends SourceInfoAwareJsNode implements JsStatement {
+public class JsForIn extends SourceInfoAwareJsNode implements JsLoop {
     private JsStatement body;
     private JsExpression iterExpression;
     private JsExpression objectExpression;
diff --git a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsLoop.java b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsLoop.java
new file mode 100644
index 00000000000..4eb63b51712
--- /dev/null
+++ b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsLoop.java
@@ -0,0 +1,14 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.js.backend.ast;
+
+import org.jetbrains.annotations.NotNull;
+
+public interface JsLoop extends JsStatement {
+    @NotNull
+    @Override
+    JsStatement deepCopy();
+}
diff --git a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsVisitor.kt b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsVisitor.kt
index e06e060057f..e9dadd6c5c6 100644
--- a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsVisitor.kt
+++ b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsVisitor.kt
@@ -64,7 +64,7 @@ abstract class JsVisitor {
             visitElement(x)
 
     open fun visitDoWhile(x: JsDoWhile): Unit =
-            visitElement(x)
+            visitLoop(x)
 
     open fun visitEmpty(x: JsEmpty): Unit =
             visitElement(x)
@@ -73,10 +73,10 @@ abstract class JsVisitor {
             visitElement(x)
 
     open fun visitFor(x: JsFor): Unit =
-            visitElement(x)
+            visitLoop(x)
 
     open fun visitForIn(x: JsForIn): Unit =
-            visitElement(x)
+            visitLoop(x)
 
     open fun visitFunction(x: JsFunction): Unit =
             visitElement(x)
@@ -90,6 +90,9 @@ abstract class JsVisitor {
     open fun visitLabel(x: JsLabel): Unit =
             visitElement(x)
 
+    open fun visitLoop(x: JsLoop): Unit =
+        visitElement(x)
+
     open fun visitNameRef(nameRef: JsNameRef): Unit =
             visitElement(nameRef)
 
@@ -151,7 +154,7 @@ abstract class JsVisitor {
             visitElement(x)
 
     open fun visitWhile(x: JsWhile): Unit =
-            visitElement(x)
+            visitLoop(x)
 
     open fun visitDocComment(comment: JsDocComment): Unit =
             visitElement(comment)
diff --git a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsVisitorWithContext.java b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsVisitorWithContext.java
index 95c5dc6945d..9dd219f35c6 100644
--- a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsVisitorWithContext.java
+++ b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsVisitorWithContext.java
@@ -104,6 +104,7 @@ public abstract class JsVisitorWithContext {
     }
 
     public void endVisit(@NotNull JsDoWhile x, @NotNull JsContext ctx) {
+        endVisit((JsLoop) x, ctx);
     }
 
     public void endVisit(@NotNull JsEmpty x, @NotNull JsContext ctx) {
@@ -113,9 +114,11 @@ public abstract class JsVisitorWithContext {
     }
 
     public void endVisit(@NotNull JsFor x, @NotNull JsContext ctx) {
+        endVisit((JsLoop) x, ctx);
     }
 
     public void endVisit(@NotNull JsForIn x, @NotNull JsContext ctx) {
+        endVisit((JsLoop) x, ctx);
     }
 
     public void endVisit(@NotNull JsFunction x, @NotNull JsContext ctx) {
@@ -132,6 +135,9 @@ public abstract class JsVisitorWithContext {
     public void endVisit(@NotNull JsLabel x, @NotNull JsContext ctx) {
     }
 
+    public void endVisit(@NotNull JsLoop x, @NotNull JsContext ctx) {
+    }
+
     public void endVisit(@NotNull JsName x, @NotNull JsContext ctx) {
     }
 
@@ -202,6 +208,7 @@ public abstract class JsVisitorWithContext {
     }
 
     public void endVisit(@NotNull JsWhile x, @NotNull JsContext ctx) {
+        endVisit((JsLoop) x, ctx);
     }
 
     public boolean visit(@NotNull JsArrayAccess x, @NotNull JsContext ctx) {
@@ -253,7 +260,7 @@ public abstract class JsVisitorWithContext {
     }
 
     public boolean visit(@NotNull JsDoWhile x, @NotNull JsContext ctx) {
-        return true;
+        return visit((JsLoop) x, ctx);
     }
 
     public boolean visit(@NotNull JsEmpty x, @NotNull JsContext ctx) {
@@ -265,11 +272,11 @@ public abstract class JsVisitorWithContext {
     }
 
     public boolean visit(@NotNull JsFor x, @NotNull JsContext ctx) {
-        return true;
+        return visit((JsLoop) x, ctx);
     }
 
     public boolean visit(@NotNull JsForIn x, @NotNull JsContext ctx) {
-        return true;
+        return visit((JsLoop) x, ctx);
     }
 
     public boolean visit(@NotNull JsFunction x, @NotNull JsContext ctx) {
@@ -288,6 +295,10 @@ public abstract class JsVisitorWithContext {
         return true;
     }
 
+    public boolean visit(@NotNull JsLoop x, @NotNull JsContext ctx) {
+        return true;
+    }
+
     public boolean visit(@NotNull JsName x, @NotNull JsContext ctx) {
         return true;
     }
@@ -369,7 +380,7 @@ public abstract class JsVisitorWithContext {
     }
 
     public boolean visit(@NotNull JsWhile x, @NotNull JsContext ctx) {
-        return true;
+        return visit((JsLoop) x, ctx);
     }
 
     protected abstract  <T extends JsNode> T doAccept(T node);
diff --git a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsWhile.java b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsWhile.java
index 91983b0815d..1c7c312f299 100644
--- a/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsWhile.java
+++ b/js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsWhile.java
@@ -10,7 +10,7 @@ import org.jetbrains.annotations.NotNull;
 /**
  * A JavaScript <code>while</code> statement.
  */
-public class JsWhile extends SourceInfoAwareJsNode implements JsStatement {
+public class JsWhile extends SourceInfoAwareJsNode implements JsLoop {
     protected JsStatement body;
     protected JsExpression condition;
 
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/DoWhileGuardElimination.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/DoWhileGuardElimination.kt
index 4e837e41c57..bea916cfbbe 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/DoWhileGuardElimination.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/DoWhileGuardElimination.kt
@@ -123,17 +123,9 @@ internal class DoWhileGuardElimination(private val root: JsStatement) {
 
             private fun isInLoop() = loopLevel > 0
 
-            override fun visitDoWhile(x: JsDoWhile) = enterLoop { super.visitDoWhile(x) }
-
-            override fun visitWhile(x: JsWhile) = enterLoop { super.visitWhile(x) }
-
-            override fun visitFor(x: JsFor) = enterLoop { super.visitFor(x) }
-
-            override fun visitForIn(x: JsForIn) = enterLoop { super.visitForIn(x) }
-
-            private inline fun enterLoop(action: () -> Unit) {
+            override fun visitLoop(x: JsLoop) {
                 loopLevel++
-                action()
+                super.visitLoop(x)
                 loopLevel--
             }
 
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/LabeledBlockToDoWhileTransformation.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/LabeledBlockToDoWhileTransformation.kt
index 53898bbc7ae..cd91f0db600 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/LabeledBlockToDoWhileTransformation.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/LabeledBlockToDoWhileTransformation.kt
@@ -28,14 +28,6 @@ object LabeledBlockToDoWhileTransformation {
         }
     }
 
-    fun JsStatement.isLoop(): Boolean = when (this) {
-        is JsWhile,
-        is JsDoWhile,
-        is JsFor,
-        is JsForIn -> true
-        else -> false
-    }
-
     fun apply(root: JsNode) {
         object : JsVisitorWithContextImpl() {
             val loopStack = Stack<JsStatement>()
@@ -58,28 +50,18 @@ object LabeledBlockToDoWhileTransformation {
             }
 
             override fun visit(x: JsLabel, ctx: JsContext<JsNode>): Boolean {
-                if (x.statement.isLoop()) {
+                if (x.statement is JsLoop) {
                     loopLabels[x.statement] = x
                 }
                 return true
             }
 
-            override fun visit(x: JsWhile, ctx: JsContext<JsNode>) = visitLoop(x)
-            override fun visit(x: JsDoWhile, ctx: JsContext<JsNode>) = visitLoop(x)
-            override fun visit(x: JsFor, ctx: JsContext<JsNode>) = visitLoop(x)
-            override fun visit(x: JsForIn, ctx: JsContext<JsNode>) = visitLoop(x)
-
-            override fun endVisit(x: JsWhile, ctx: JsContext<JsNode>) = endVisitLoop(x, ctx)
-            override fun endVisit(x: JsDoWhile, ctx: JsContext<JsNode>) = endVisitLoop(x, ctx)
-            override fun endVisit(x: JsFor, ctx: JsContext<JsNode>) = endVisitLoop(x, ctx)
-            override fun endVisit(x: JsForIn, ctx: JsContext<JsNode>) = endVisitLoop(x, ctx)
-
-            private fun visitLoop(x: JsStatement): Boolean {
+            override fun visit(x: JsLoop, ctx: JsContext<JsNode>): Boolean {
                 loopStack.push(x)
                 return true
             }
 
-            private fun endVisitLoop(x: JsStatement, ctx: JsContext<JsNode>) {
+            override fun endVisit(x: JsLoop, ctx: JsContext<JsNode>) {
                 loopStack.pop()
                 if (loopsToLabel.contains(x)) {
                     // Reuse loop label if present. Otherwise create new label.
@@ -102,11 +84,8 @@ object LabeledBlockToDoWhileTransformation {
      */
     private fun labelLoopBreaksAndContinues(loop: JsStatement, fakeLoops: Set<JsDoWhile>, label: JsNameRef) {
         object : JsVisitorWithContextImpl() {
-            override fun visit(x: JsWhile, ctx: JsContext<JsNode>): Boolean = visitLoop(x)
-            override fun visit(x: JsDoWhile, ctx: JsContext<JsNode>): Boolean = visitLoop(x)
-            override fun visit(x: JsFor, ctx: JsContext<JsNode>): Boolean = visitLoop(x)
-            override fun visit(x: JsForIn, ctx: JsContext<JsNode>): Boolean = visitLoop(x)
-            private fun visitLoop(x: JsStatement): Boolean = fakeLoops.contains(x) || x === loop
+            override fun visit(x: JsLoop, ctx: JsContext<JsNode>): Boolean =
+                fakeLoops.contains(x) || x === loop
 
             override fun endVisit(x: JsBreak, ctx: JsContext<JsNode>) {
                 if (x.label == null)
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/TemporaryVariableElimination.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/TemporaryVariableElimination.kt
index 1ae9ae37e8c..4a393eaca9a 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/TemporaryVariableElimination.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/TemporaryVariableElimination.kt
@@ -183,13 +183,7 @@ internal class TemporaryVariableElimination(private val function: JsFunction) {
                 }
             }
 
-            override fun visitFor(x: JsFor) = withNewScope { super.visitFor(x) }
-
-            override fun visitForIn(x: JsForIn) = withNewScope { super.visitForIn(x) }
-
-            override fun visitWhile(x: JsWhile) = withNewScope { super.visitWhile(x) }
-
-            override fun visitDoWhile(x: JsDoWhile) = withNewScope { super.visitDoWhile(x) }
+            override fun visitLoop(x: JsLoop) = withNewScope { super.visitLoop(x) }
 
             override fun visitIf(x: JsIf) {
                 accept(x.ifExpression)
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ContinueReplacingVisitor.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ContinueReplacingVisitor.kt
index 5b136165bdc..6a53bef49b8 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ContinueReplacingVisitor.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ContinueReplacingVisitor.kt
@@ -34,53 +34,14 @@ class ContinueReplacingVisitor(val loopLabelName: JsName?, val guardLabelName: J
         return false
     }
 
-    override fun visit(x: JsWhile, ctx: JsContext<JsNode>): Boolean {
+    override fun visit(x: JsLoop, ctx: JsContext<JsNode>): Boolean {
         if (loopLabelName == null) return false
 
         loopNestingLevel++
         return super.visit(x, ctx)
     }
 
-    override fun endVisit(x: JsWhile, ctx: JsContext<JsNode>) {
-        super.endVisit(x, ctx)
-        if (loopLabelName == null) return
-        loopNestingLevel--
-    }
-
-    override fun visit(x: JsDoWhile, ctx: JsContext<JsNode>): Boolean {
-        if (loopLabelName == null) return false
-
-        loopNestingLevel++
-        return super.visit(x, ctx)
-    }
-
-    override fun endVisit(x: JsDoWhile, ctx: JsContext<JsNode>) {
-        super.endVisit(x, ctx)
-        if (loopLabelName == null) return
-        loopNestingLevel--
-    }
-
-    override fun visit(x: JsFor, ctx: JsContext<JsNode>): Boolean {
-        if (loopLabelName == null) return false
-
-        loopNestingLevel++
-        return super.visit(x, ctx)
-    }
-
-    override fun endVisit(x: JsFor, ctx: JsContext<JsNode>) {
-        super.endVisit(x, ctx)
-        if (loopLabelName == null) return
-        loopNestingLevel--
-    }
-
-    override fun visit(x: JsForIn, ctx: JsContext<JsNode>): Boolean {
-        if (loopLabelName == null) return false
-
-        loopNestingLevel++
-        return super.visit(x, ctx)
-    }
-
-    override fun endVisit(x: JsForIn, ctx: JsContext<JsNode>) {
+    override fun endVisit(x: JsLoop, ctx: JsContext<JsNode>) {
         super.endVisit(x, ctx)
         if (loopLabelName == null) return
         loopNestingLevel--