diff --git a/js/js.tests/test/org/jetbrains/k2js/test/semantics/CompareToTest.java b/js/js.tests/test/org/jetbrains/k2js/test/semantics/CompareToTest.java
new file mode 100644
index 00000000000..c5bd194fa8e
--- /dev/null
+++ b/js/js.tests/test/org/jetbrains/k2js/test/semantics/CompareToTest.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.k2js.test.semantics;
+
+public final class CompareToTest extends AbstractExpressionTest {
+
+    public CompareToTest() {
+        super("compareTo/");
+    }
+
+    public void testCustomCompareToMethod() throws Exception {
+        checkFooBoxIsOk();
+    }
+}
\ No newline at end of file
diff --git a/js/js.tests/test/org/jetbrains/k2js/test/semantics/NumberTest.java b/js/js.tests/test/org/jetbrains/k2js/test/semantics/NumberTest.java
index 3b707b628b8..b52a1fc3948 100644
--- a/js/js.tests/test/org/jetbrains/k2js/test/semantics/NumberTest.java
+++ b/js/js.tests/test/org/jetbrains/k2js/test/semantics/NumberTest.java
@@ -70,6 +70,10 @@ public final class NumberTest extends SingleFileTranslationTest {
         checkFooBoxIsOk();
     }
 
+    public void testNumberIsCheck() throws Exception {
+        checkFooBoxIsOk();
+    }
+
     public void testConversionsWithoutTruncation() throws Exception {
         checkFooBoxIsOk();
     }
diff --git a/js/js.translator/testData/expression/compareTo/cases/customCompareToMethod.kt b/js/js.translator/testData/expression/compareTo/cases/customCompareToMethod.kt
new file mode 100644
index 00000000000..3184d92f26a
--- /dev/null
+++ b/js/js.translator/testData/expression/compareTo/cases/customCompareToMethod.kt
@@ -0,0 +1,40 @@
+package foo
+
+class A(val value: Int) : Comparable<A> {
+    override public fun compareTo(other: A): Int = other.value compareTo value
+}
+
+class B(val value: Int)
+
+fun testExtensionFunctionAsCompareTo() {
+    val compareTo: B.( B ) -> Int = { (other) -> other.value compareTo this.value }
+
+    val x: B = B(100)
+    val y: B = B(200)
+
+    assertEquals(false, x < y, "ext fun: x < y")
+    assertEquals(true, x > y, "ext fun: x > y")
+    assertEquals(1, x compareTo y, "ext fun: x compareTo y")
+}
+
+fun testMethodAsCompareTo() {
+    val x: A = A(100)
+    val y: A = A(200)
+
+    assertEquals(false, x < y, "meth: x < y")
+    assertEquals(true, x > y, "meth: x > y")
+    assertEquals(1, x compareTo y, "meth: x compareTo y")
+
+    assertEquals(false, (x: Comparable<A>) < y, "meth: (x: Comparable<A>) < y")
+    assertEquals(true, (x: Comparable<A>) > y, "meth: (x: Comparable<A>) > y")
+    assertEquals(1, (x: Comparable<A>) compareTo y, "meth: (x: Comparable<A>) compareTo y")
+}
+
+fun box(): String {
+
+    testExtensionFunctionAsCompareTo()
+
+    testMethodAsCompareTo()
+
+    return "OK"
+}
\ No newline at end of file
diff --git a/js/js.translator/testData/number/cases/numberCompareTo.kt b/js/js.translator/testData/number/cases/numberCompareTo.kt
index 4b64ce4b1fa..762978e3520 100644
--- a/js/js.translator/testData/number/cases/numberCompareTo.kt
+++ b/js/js.translator/testData/number/cases/numberCompareTo.kt
@@ -10,6 +10,7 @@ fun id(s: String, value: Int): Int {
 fun box(): String {
 
     assertEquals(-1, 1.compareTo(2))
+    assertEquals(-1, (1: Comparable<Int>).compareTo(2))
 
     assertEquals(-1, 1 compareTo 2)
     assertEquals(-1, 1 compareTo (2:Short))
@@ -31,6 +32,7 @@ fun box(): String {
 
     assertEquals(-1, (1: Short) compareTo 2)
     assertEquals(-1, (1: Short) compareTo (2:Short))
+    assertEquals(-1, ((1: Short): Comparable<Short>) compareTo (2:Short))
     assertEquals(-1, (1: Short) compareTo (2:Byte))
     assertEquals(-1, (1: Short) compareTo 2.0)
     assertEquals(-1, (1: Short) compareTo 2.0f)
@@ -38,6 +40,7 @@ fun box(): String {
     assertEquals(1, (10: Byte) compareTo 2)
     assertEquals(1, (10: Byte) compareTo (2:Short))
     assertEquals(1, (10: Byte) compareTo (2:Byte))
+    assertEquals(1, ((10: Byte): Comparable<Byte>) compareTo (2:Byte))
     assertEquals(1, (10: Byte) compareTo 2.0)
     assertEquals(1, (10: Byte) compareTo 2.0f)
 
@@ -45,6 +48,7 @@ fun box(): String {
     assertEquals(0, 2.0 compareTo (2:Short))
     assertEquals(0, 2.0 compareTo (2:Byte))
     assertEquals(0, 2.0 compareTo 2.0)
+    assertEquals(0, (2.0: Comparable<Double>) compareTo 2.0)
     assertEquals(0, 2.0 compareTo 2.0f)
 
     assertEquals(1, 3.0f compareTo 2)
@@ -52,6 +56,7 @@ fun box(): String {
     assertEquals(1, 3.0f compareTo (2:Byte))
     assertEquals(1, 3.0f compareTo 2.0)
     assertEquals(1, 3.0f compareTo 2.0f)
+    assertEquals(1, (3.0f: Comparable<Float>) compareTo 2.0f)
 
     assertEquals(1, id("A", 10) compareTo id("B", 5))
     assertEquals("AB", global)
diff --git a/js/js.translator/testData/number/cases/numberIsCheck.kt b/js/js.translator/testData/number/cases/numberIsCheck.kt
new file mode 100644
index 00000000000..963f2eb2438
--- /dev/null
+++ b/js/js.translator/testData/number/cases/numberIsCheck.kt
@@ -0,0 +1,49 @@
+package foo
+
+// For now, check is Byte(is Short, is Int is Float, is Double) translates to typeof ... == "number"
+
+fun testNum(numX: Number) {
+    assertEquals(true, numX is Number, "numX is Number")
+    assertEquals(true, numX is Int, "numX is Int")
+
+    assertEquals(true, numX is Short, "numX is Short")
+    assertEquals(true, numX is Byte, "numX is Byte")
+
+    assertEquals(true, numX is Double, "numX is Double")
+    assertEquals(true, numX is Float, "numX is Float")
+}
+
+fun testAny(anyX: Any) {
+    assertEquals(true, anyX is Number, "anyX is Number")
+    assertEquals(true, anyX is Int, "anyX is Int")
+
+    assertEquals(true, anyX is Short, "anyX is Short")
+    assertEquals(true, anyX is Byte, "anyX is Byte")
+
+    assertEquals(true, anyX is Double, "anyX is Double")
+    assertEquals(true, anyX is Float, "anyX is Float")
+}
+
+fun box(): String {
+    val intX = 100
+
+    assertEquals(true, intX is Number, "intX is Number")
+    assertEquals(true, intX is Int, "intX is Int")
+
+    var anyX: Any = "A"
+    assertEquals(false, anyX is Number, "anyX is Number")
+
+    testNum(100)
+    testNum(100: Short)
+    testNum(100: Byte)
+    testNum(100.0)
+    testNum(100.0f)
+
+    testAny(100)
+    testAny(100: Short)
+    testAny(100: Byte)
+    testAny(100.0)
+    testAny(100.0f)
+
+    return "OK"
+}
\ No newline at end of file