diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/context/StandardClasses.java b/js/js.translator/src/org/jetbrains/k2js/translate/context/StandardClasses.java
index 6a64754a684..ffc679328ce 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/context/StandardClasses.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/context/StandardClasses.java
@@ -101,7 +101,10 @@ public final class StandardClasses {
         standardClasses.declare().forFQ("jet.Iterator").kotlinClass("Iterator").methods("next").properties("hasNext");
 
         standardClasses.declare().forFQ("jet.IntRange").kotlinClass("NumberRange")
-                .methods("iterator", "contains").properties("start", "size", "end", "reversed");
+                .methods("iterator", "contains").properties("start", "end", "increment");
+
+        standardClasses.declare().forFQ("jet.IntSequence").kotlinClass("NumberSequence")
+                .methods("iterator", "contains").properties("start", "end", "increment");
 
         standardClasses.declare().forFQ("jet.Any.toString").kotlinFunction("toString");
 
diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/expression/foreach/RangeForTranslator.java b/js/js.translator/src/org/jetbrains/k2js/translate/expression/foreach/RangeForTranslator.java
index c318727ea35..48a086959dd 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/expression/foreach/RangeForTranslator.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/expression/foreach/RangeForTranslator.java
@@ -54,28 +54,24 @@ public final class RangeForTranslator extends ForTranslator {
     @NotNull
     private final TemporaryVariable rangeExpression;
     @NotNull
-    private final TemporaryVariable incrVar;
-    @NotNull
     private final TemporaryVariable start;
     @NotNull
     private final TemporaryVariable end;
+    @NotNull
+    private final TemporaryVariable increment;
 
     private RangeForTranslator(@NotNull JetForExpression forExpression, @NotNull TranslationContext context) {
         super(forExpression, context);
         rangeExpression = context.declareTemporary(Translation.translateAsExpression(getLoopRange(expression), context));
-        JsExpression isReversed = callFunction("get_reversed");
-        JsConditional incrVarValue = new JsConditional(isReversed,
-                                                       program().getNumberLiteral(-1),
-                                                       program().getNumberLiteral(1));
-        incrVar = context().declareTemporary(incrVarValue);
         start = context().declareTemporary(callFunction("get_start"));
-        end = context().declareTemporary(sum(callFunction("get_end"), incrVar.reference()));
+        end = context().declareTemporary(callFunction("get_end"));
+        increment = context().declareTemporary(callFunction("get_increment"));
     }
 
     @NotNull
     private JsBlock translate() {
         List<JsStatement> blockStatements = Lists.newArrayList();
-        blockStatements.add(temporariesInitialization(rangeExpression, incrVar, start, end).makeStmt());
+        blockStatements.add(temporariesInitialization(rangeExpression, start, end, increment).makeStmt());
         blockStatements.add(generateForExpression());
         return new JsBlock(blockStatements);
     }
@@ -94,12 +90,12 @@ public final class RangeForTranslator extends ForTranslator {
 
     @NotNull
     private JsExpression getCondition() {
-        return inequality(parameterName.makeRef(), end.reference());
+        return lessThanEq(parameterName.makeRef(), end.reference());
     }
 
     @NotNull
     private JsExpression getIncrExpression() {
-        return addAssign(parameterName.makeRef(), incrVar.reference());
+        return addAssign(parameterName.makeRef(), increment.reference());
     }
 
     @NotNull
diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/intrinsic/functions/factories/PrimitiveBinaryOperationFIF.java b/js/js.translator/src/org/jetbrains/k2js/translate/intrinsic/functions/factories/PrimitiveBinaryOperationFIF.java
index e6a59687b51..ef77f1049fe 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/intrinsic/functions/factories/PrimitiveBinaryOperationFIF.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/intrinsic/functions/factories/PrimitiveBinaryOperationFIF.java
@@ -51,12 +51,10 @@ public enum PrimitiveBinaryOperationFIF implements FunctionIntrinsicFactory {
             assert arguments.size() == 1 : "RangeTo must have one argument.";
             assert rangeStart != null;
             JsExpression rangeEnd = arguments.get(0);
-            JsBinaryOperation rangeSize = sum(subtract(rangeEnd, rangeStart),
-                                              context.program().getNumberLiteral(1));
             JsNameRef expr = AstUtil.newQualifiedNameRef("Kotlin.NumberRange");
             HasArguments numberRangeConstructorInvocation = context.isEcma5() ? new JsInvocation(expr) : new JsNew(expr);
             //TODO: add tests and correct expression for reversed ranges.
-            setArguments(numberRangeConstructorInvocation, rangeStart, rangeSize, /*range is not reversed*/JsLiteral.FALSE);
+            setArguments(numberRangeConstructorInvocation, rangeStart, rangeEnd);
             return (JsExpression) numberRangeConstructorInvocation;
         }
     };
diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/utils/JsAstUtils.java b/js/js.translator/src/org/jetbrains/k2js/translate/utils/JsAstUtils.java
index ec6f9fdaadc..44ea882b910 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/utils/JsAstUtils.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/utils/JsAstUtils.java
@@ -115,6 +115,11 @@ public final class JsAstUtils {
         return new JsBinaryOperation(JsBinaryOperator.REF_NEQ, arg1, arg2);
     }
 
+    @NotNull
+    public static JsBinaryOperation lessThanEq(@NotNull JsExpression arg1, @NotNull JsExpression arg2) {
+        return new JsBinaryOperation(JsBinaryOperator.LTE, arg1, arg2);
+    }
+
     @NotNull
     public static JsExpression assignment(@NotNull JsExpression left, @NotNull JsExpression right) {
         return new JsBinaryOperation(JsBinaryOperator.ASG, left, right);
diff --git a/js/js.translator/testFiles/kotlin_lib.js b/js/js.translator/testFiles/kotlin_lib.js
index 7043e0376f7..3ea5856d088 100644
--- a/js/js.translator/testFiles/kotlin_lib.js
+++ b/js/js.translator/testFiles/kotlin_lib.js
@@ -63,12 +63,12 @@ var kotlin = {set:function (receiver, key, value) {
         return args === null || args === undefined ? [] : args.slice();
     };
 
-    Kotlin.intUpto = function (from, limit) {
-        return Kotlin.$new(Kotlin.NumberRange)(from, limit - from + 1, false);
+    Kotlin.intUpto = function (from, to) {
+        return Kotlin.$new(Kotlin.NumberRange)(from, to);
     };
 
-    Kotlin.intDownto = function (from, limit) {
-        return Kotlin.$new(Kotlin.NumberRange)(from, from - limit + 1, true);
+    Kotlin.intDownto = function (from, to) {
+        return Kotlin.$new(Kotlin.NumberSequence)(from, to, -1);
     };
 
     Kotlin.modules = {};
@@ -344,23 +344,17 @@ var kotlin = {set:function (receiver, key, value) {
     };
 
     Kotlin.RangeIterator = Kotlin.$createClass(Kotlin.Iterator, {
-        initialize: function (start, count, reversed) {
+        initialize: function (start, end, increment) {
             this.$start = start;
-            this.$count = count;
-            this.$reversed = reversed;
-            this.$i = this.get_start();
+            this.$end = end;
+            this.$increment = increment;
+            this.$i = start;
         },
         get_start: function () {
             return this.$start;
         },
-        get_count: function () {
-            return this.$count;
-        },
-        set_count: function (tmp$0) {
-            this.$count = tmp$0;
-        },
-        get_reversed: function () {
-            return this.$reversed;
+        get_end: function () {
+            return this.$end;
         },
         get_i: function () {
             return this.$i;
@@ -369,49 +363,54 @@ var kotlin = {set:function (receiver, key, value) {
             this.$i = tmp$0;
         },
         next: function () {
-            this.set_count(this.get_count() - 1);
-            if (this.get_reversed()) {
-                this.set_i(this.get_i() - 1);
-                return this.get_i() + 1;
-            }
-            else {
-                this.set_i(this.get_i() + 1);
-                return this.get_i() - 1;
-            }
+            var value = this.$i;
+            this.set_i(this.$i + this.$increment)
+            return value;
         },
         get_hasNext: function () {
-            return this.get_count() > 0;
+            return this.$increment > 0 ? this.$next <= this.$end : this.$next >= this.$end;
         }
     });
 
     Kotlin.NumberRange = Kotlin.$createClass({
-        initialize: function (start, size, reversed) {
+        initialize: function (start, end) {
             this.$start = start;
-            this.$size = size;
-            this.$reversed = reversed;
+            this.$end = end;
         },
         get_start: function () {
             return this.$start;
         },
-        get_size: function () {
-            return this.$size;
-        },
-        get_reversed: function () {
-            return this.$reversed;
-        },
         get_end: function () {
-            return this.get_reversed() ? this.get_start() - this.get_size() + 1 : this.get_start() + this.get_size() - 1;
+            return this.$end;
+        },
+        get_increment: function () {
+            return 1;
         },
         contains: function (number) {
-            if (this.get_reversed()) {
-                return number <= this.get_start() && number > this.get_start() - this.get_size();
-            }
-            else {
-                return number >= this.get_start() && number < this.get_start() + this.get_size();
-            }
+            return this.$start <= number && number <= this.$end;
         },
         iterator: function () {
-            return Kotlin.$new(Kotlin.RangeIterator)(this.get_start(), this.get_size(), this.get_reversed());
+            return Kotlin.$new(Kotlin.RangeIterator)(this.get_start(), this.get_end());
+        }
+    });
+
+    Kotlin.NumberSequence = Kotlin.$createClass({
+        initialize: function (start, end, increment) {
+            this.$start = start;
+            this.$end = end;
+            this.$increment = increment;
+        },
+        get_start: function () {
+            return this.$start;
+        },
+        get_end: function () {
+            return this.$end;
+        },
+        get_increment: function () {
+            return this.$increment;
+        },
+        iterator: function () {
+            return Kotlin.$new(Kotlin.RangeIterator)(this.get_start(), this.get_end(), this.get_increment());
         }
     });
 
@@ -483,7 +482,7 @@ var kotlin = {set:function (receiver, key, value) {
     };
 
     Kotlin.arrayIndices = function (arr) {
-        return Kotlin.$new(Kotlin.NumberRange)(0, arr.length);
+        return Kotlin.$new(Kotlin.NumberRange)(0, arr.length - 1);
     };
 
     Kotlin.arrayIterator = function (array) {