diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsBridgesConstruction.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsBridgesConstruction.kt
index 4a1456275db..bfa305129b8 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsBridgesConstruction.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsBridgesConstruction.kt
@@ -9,18 +9,16 @@ import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.JsLoweredDeclarationOrigin
 import org.jetbrains.kotlin.ir.backend.js.ir.JsIrArithBuilder
 import org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.varargParameterIndex
-import org.jetbrains.kotlin.ir.backend.js.utils.eraseGenerics
-import org.jetbrains.kotlin.ir.backend.js.utils.getJsNameOrKotlinName
 import org.jetbrains.kotlin.ir.backend.js.utils.hasStableJsName
+import org.jetbrains.kotlin.ir.backend.js.utils.jsFunctionSignature
 import org.jetbrains.kotlin.ir.builders.*
-import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
+import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
+import org.jetbrains.kotlin.ir.declarations.IrValueDeclaration
+import org.jetbrains.kotlin.ir.declarations.IrVariable
 import org.jetbrains.kotlin.ir.expressions.IrExpression
-import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.classifierOrNull
-import org.jetbrains.kotlin.ir.types.isUnit
 import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
-import org.jetbrains.kotlin.ir.util.render
-import org.jetbrains.kotlin.name.Name
 
 class JsBridgesConstruction(context: JsIrBackendContext) : BridgesConstruction<JsIrBackendContext>(context) {
 
@@ -35,21 +33,8 @@ class JsBridgesConstruction(context: JsIrBackendContext) : BridgesConstruction<J
     private val primitiveArrays = context.intrinsics.primitiveArrays
     private val primitiveToLiteralConstructor = context.intrinsics.primitiveToLiteralConstructor
 
-    private fun IrType.getJsInlinedClass() = context.inlineClassesUtils.getInlinedClass(this)
-
-    override fun getFunctionSignature(function: IrSimpleFunction): JsSignature =
-        if (function.hasStableJsName(context)) {
-            JsStableNameSignature(function.getJsNameOrKotlinName())
-        } else {
-            JsNonStableSignature(
-                function.name,
-                function.extensionReceiverParameter?.type?.eraseGenerics(context.irBuiltIns),
-                function.valueParameters.map { it.type.eraseGenerics(context.irBuiltIns) },
-                function.returnType.takeIf {
-                    it.getJsInlinedClass() != null || it.isUnit()
-                }?.eraseGenerics(context.irBuiltIns)
-            )
-        }
+    override fun getFunctionSignature(function: IrSimpleFunction) =
+        jsFunctionSignature(function, context)
 
     override fun getBridgeOrigin(bridge: IrSimpleFunction): IrDeclarationOrigin =
         when {
@@ -167,24 +152,3 @@ class JsBridgesConstruction(context: JsIrBackendContext) : BridgesConstruction<J
         return createTmpVariable(varargCopiedAsArray, nameHint = varargElement.name.asString())
     }
 }
-
-interface JsSignature {
-    val name: Name
-}
-
-data class JsNonStableSignature(
-    override val name: Name,
-    val extensionReceiverType: IrType?,
-    val valueParametersType: List<IrType>,
-    val returnType: IrType?,
-) : JsSignature {
-    override fun toString(): String {
-        val er = extensionReceiverType?.let { "(er: ${it.render()}) " } ?: ""
-        val parameters = valueParametersType.joinToString(", ") { it.render() }
-        return "[$er$name($parameters) -> ${returnType?.let { " -> ${it.render()}" } ?: ""}]"
-    }
-}
-
-data class JsStableNameSignature(
-    override val name: Name,
-) : JsSignature
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/TypeOperatorLowering.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/TypeOperatorLowering.kt
index fbf362e6fcc..9d33262bbbf 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/TypeOperatorLowering.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/TypeOperatorLowering.kt
@@ -9,7 +9,6 @@ import org.jetbrains.kotlin.backend.common.BodyLoweringPass
 import org.jetbrains.kotlin.backend.common.compilationException
 import org.jetbrains.kotlin.backend.common.ir.isPure
 import org.jetbrains.kotlin.ir.IrStatement
-import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.ir.JsIrArithBuilder
 import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
@@ -19,7 +18,6 @@ import org.jetbrains.kotlin.ir.declarations.IrDeclarationBase
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationParent
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrCompositeImpl
-import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrTypeOperatorCallImpl
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
@@ -229,37 +227,13 @@ class TypeOperatorLowering(val context: JsIrBackendContext) : BodyLoweringPass {
              * └─────────────┻─────────────────────────────┴───────────────────────────────┘
              * ```
              * Note: advanced check is performed when casting to primitive types, array types, function types, or interfaces.
-             *
-             * If we statically know that this is an upcast, we try to generate no checks.
-             * In this case, the following logic is applied:
-             * ```
-             *               ┌─────────────┬─────────────┐
-             *               │ to non-null │ to nullable │
-             * ┌─────────────╋━━━━━━━━━━━━━┻━━━━━━━━━━━━━┫
-             * │from non-null┃           true            │
-             * ├─────────────╋─────────────┬─────────────┤
-             * │from nullable┃ null check  │    true     │
-             * └─────────────┻─────────────┴─────────────┘
-             * ```
              */
             private fun generateTypeCheck(argument: () -> IrExpression, toType: IrType): IrExpression {
                 val toNotNullable = toType.makeNotNull()
                 val argumentInstance = argument()
-                val fromType = argumentInstance.type
-                val fromNotNullable = fromType.makeNotNull()
-
-                val isFromNullable = fromType.isNullable()
-                val isToNullable = toType.isNullable()
-
-                if (fromNotNullable !is IrDynamicType && fromNotNullable.isSubtypeOf(toNotNullable, context.typeSystem)) {
-                    // This is an upcast
-                    return when {
-                        isFromNullable && !isToNullable -> calculator.run { not(nullCheck(argument())) }
-                        else -> IrConstImpl.constTrue(UNDEFINED_OFFSET, UNDEFINED_OFFSET, context.irBuiltIns.booleanType)
-                    }
-                }
-
                 val instanceCheck = generateTypeCheckNonNull(argumentInstance, toNotNullable)
+                val isFromNullable = argumentInstance.type.isNullable()
+                val isToNullable = toType.isNullable()
                 val isNativeCheck = !advancedCheckRequired(toNotNullable)
 
                 return when {
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt
index d16335ddcad..eb082206c3b 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt
@@ -14,7 +14,11 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.symbols.IrReturnableBlockSymbol
 import org.jetbrains.kotlin.ir.types.isUnit
-import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.util.file
+import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
+import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
+import org.jetbrains.kotlin.ir.util.isInterface
+import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.js.common.isES5IdentifierPart
@@ -137,17 +141,22 @@ fun jsFunctionSignature(declaration: IrFunction, context: JsIrBackendContext): S
     val nameBuilder = StringBuilder()
     nameBuilder.append(declarationName)
 
+    // TODO should we skip type parameters and use upper bound of type parameter when print type of value parameters?
+    declaration.typeParameters.ifNotEmpty {
+        nameBuilder.append("_\$t")
+        joinTo(nameBuilder, "") { "_${it.name.asString()}" }
+    }
     declaration.extensionReceiverParameter?.let {
-        nameBuilder.append("_r$${it.type.eraseGenerics(context.irBuiltIns).asString()}")
+        nameBuilder.append("_r$${it.type.asString()}")
     }
     declaration.valueParameters.ifNotEmpty {
-        joinTo(nameBuilder, "") { "_${it.type.eraseGenerics(context.irBuiltIns).asString()}" }
+        joinTo(nameBuilder, "") { "_${it.type.asString()}" }
     }
     declaration.returnType.let {
         // Return type is only used in signature for inline class and Unit types because
         // they are binary incompatible with supertypes.
         if (context.inlineClassesUtils.isTypeInlined(it) || it.isUnit()) {
-            nameBuilder.append("_ret$${it.eraseGenerics(context.irBuiltIns).asString()}")
+            nameBuilder.append("_ret$${it.asString()}")
         }
     }
 
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/TypeTranformer.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/TypeTranformer.kt
index f3b100a223b..25a00839e3e 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/TypeTranformer.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/TypeTranformer.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
diff --git a/compiler/testData/codegen/boxError/semantic/missedBody.kt b/compiler/testData/codegen/boxError/semantic/missedBody.kt
index 17aa09f87fe..1572e7dac24 100644
--- a/compiler/testData/codegen/boxError/semantic/missedBody.kt
+++ b/compiler/testData/codegen/boxError/semantic/missedBody.kt
@@ -4,9 +4,9 @@
 // MODULE: lib
 // FILE: t.kt
 
-fun bar(a: String, b: String): Any
+fun bar(a: String, b: String): String
 
-fun foo(): Any {
+fun foo(): String {
     return bar("O", "K")
 }
 
@@ -17,4 +17,4 @@ fun box(): String {
     val r = foo()
     if (r is String) return r
     return "OK"
-}
+}
\ No newline at end of file
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/BoxJsTestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/BoxJsTestGenerated.java
index ee99ae02cb9..c65eb0d97bc 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/BoxJsTestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/BoxJsTestGenerated.java
@@ -2287,12 +2287,6 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
                 runTest("js/js.translator/testData/box/expression/cast/primitiveToClass.kt");
             }
 
-            @Test
-            @TestMetadata("redundantCast.kt")
-            public void testRedundantCast() throws Exception {
-                runTest("js/js.translator/testData/box/expression/cast/redundantCast.kt");
-            }
-
             @Test
             @TestMetadata("reifiedToNotNull.kt")
             public void testReifiedToNotNull() throws Exception {
@@ -2352,6 +2346,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             public void testSmartCastInFunction() throws Exception {
                 runTest("js/js.translator/testData/box/expression/cast/smartCastInFunction.kt");
             }
+
+            @Test
+            @TestMetadata("unsafeVarianceCast.kt")
+            public void testUnsafeVarianceCast() throws Exception {
+                runTest("js/js.translator/testData/box/expression/cast/unsafeVarianceCast.kt");
+            }
         }
 
         @Nested
@@ -3013,6 +3013,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
                 runTest("js/js.translator/testData/box/expression/function/overloadClassConstructorByFactoryMethod.kt");
             }
 
+            @Test
+            @TestMetadata("overloadGeneric.kt")
+            public void testOverloadGeneric() throws Exception {
+                runTest("js/js.translator/testData/box/expression/function/overloadGeneric.kt");
+            }
+
             @Test
             @TestMetadata("overloadOverridenFun.kt")
             public void testOverloadOverridenFun() throws Exception {
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrBoxJsTestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrBoxJsTestGenerated.java
index a1f5d382688..52d8087d7dc 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrBoxJsTestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrBoxJsTestGenerated.java
@@ -2683,12 +2683,6 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
                 runTest("js/js.translator/testData/box/expression/cast/primitiveToClass.kt");
             }
 
-            @Test
-            @TestMetadata("redundantCast.kt")
-            public void testRedundantCast() throws Exception {
-                runTest("js/js.translator/testData/box/expression/cast/redundantCast.kt");
-            }
-
             @Test
             @TestMetadata("reifiedToNotNull.kt")
             public void testReifiedToNotNull() throws Exception {
@@ -2748,6 +2742,12 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             public void testSmartCastInFunction() throws Exception {
                 runTest("js/js.translator/testData/box/expression/cast/smartCastInFunction.kt");
             }
+
+            @Test
+            @TestMetadata("unsafeVarianceCast.kt")
+            public void testUnsafeVarianceCast() throws Exception {
+                runTest("js/js.translator/testData/box/expression/cast/unsafeVarianceCast.kt");
+            }
         }
 
         @Nested
@@ -3397,6 +3397,12 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
                 runTest("js/js.translator/testData/box/expression/function/overloadClassConstructorByFactoryMethod.kt");
             }
 
+            @Test
+            @TestMetadata("overloadGeneric.kt")
+            public void testOverloadGeneric() throws Exception {
+                runTest("js/js.translator/testData/box/expression/function/overloadGeneric.kt");
+            }
+
             @Test
             @TestMetadata("overloadOverridenFun.kt")
             public void testOverloadOverridenFun() throws Exception {
diff --git a/js/js.translator/testData/box/expression/cast/redundantCast.kt b/js/js.translator/testData/box/expression/cast/redundantCast.kt
deleted file mode 100644
index 9de4a3aed1a..00000000000
--- a/js/js.translator/testData/box/expression/cast/redundantCast.kt
+++ /dev/null
@@ -1,150 +0,0 @@
-// EXPECTED_REACHABLE_NODES: 1306
-
-// Test that upcasts are optimized away
-
-open class Base
-
-class Derived: Base()
-
-var counter = 0
-var _derived = Derived()
-
-@JsExport
-fun getDerived(): Derived {
-    counter += 1
-    return _derived
-}
-
-@JsExport
-fun getDerivedNullable(): Derived? {
-    counter += 1
-    return _derived
-}
-
-@JsExport
-fun getDerivedNull(): Derived? {
-    counter += 1
-    return null
-}
-
-// CHECK_CONTAINS_NO_CALLS: upcast1 except=getDerived IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=upcast1 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=upcast1 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=upcast1 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun upcast1() = getDerived() as Base
-
-// CHECK_CONTAINS_NO_CALLS: upcast2 except=getDerived IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=upcast2 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=upcast2 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=upcast2 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun upcast2() = getDerived() as Base?
-
-// CHECK_BINOP_COUNT: function=upcast3 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun upcast3() = getDerivedNullable() as Base
-
-// CHECK_CONTAINS_NO_CALLS: upcast4 except=getDerivedNullable IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=upcast4 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=upcast4 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=upcast1 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun upcast4() = getDerivedNullable() as Base?
-
-// CHECK_BINOP_COUNT: function=upcast5 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun upcast5() = getDerivedNull() as Base
-
-// CHECK_CONTAINS_NO_CALLS: upcast6 except=getDerivedNull IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=upcast6 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=upcast6 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=upcast6 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun upcast6() = getDerivedNull() as Base?
-
-// CHECK_CONTAINS_NO_CALLS: safeCast1 except=getDerived IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=safeCast1 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=safeCast1 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=safeCast1 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun safeCast1() = getDerived() as? Base
-
-// CHECK_CONTAINS_NO_CALLS: safeCast2 except=getDerived IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=safeCast1 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=safeCast1 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=safeCast2 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun safeCast2() = getDerived() as? Base?
-
-// CHECK_BINOP_COUNT: function=safeCast3 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun safeCast3() = getDerivedNullable() as? Base
-
-// CHECK_CONTAINS_NO_CALLS: safeCast4 except=getDerivedNullable IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=safeCast4 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=safeCast4 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=safeCast4 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun safeCast4() = getDerivedNullable() as? Base?
-
-// CHECK_BINOP_COUNT: function=safeCast5 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun safeCast5() = getDerivedNull() as? Base
-
-// CHECK_CONTAINS_NO_CALLS: safeCast6 except=getDerivedNull IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=safeCast6 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=safeCast6 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=safeCast6 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun safeCast6() = getDerivedNull() as? Base?
-
-// CHECK_CONTAINS_NO_CALLS: upcast1 except=getDerived IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=upcast1 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=upcast1 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=instanceCheck1 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun instanceCheck1() = getDerived() is Base
-
-// CHECK_CONTAINS_NO_CALLS: upcast2 except=getDerived IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=upcast2 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=upcast2 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=instanceCheck2 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun instanceCheck2() = getDerived() is Base?
-
-// CHECK_BINOP_COUNT: function=instanceCheck3 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun instanceCheck3() = getDerivedNullable() is Base
-
-// CHECK_CONTAINS_NO_CALLS: upcast4 except=getDerivedNullable IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=upcast4 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=upcast4 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=instanceCheck4 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun instanceCheck4() = getDerivedNullable() is Base?
-
-// CHECK_BINOP_COUNT: function=instanceCheck5 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun instanceCheck5() = getDerivedNull() is Base
-
-// CHECK_CONTAINS_NO_CALLS: upcast6 except=getDerivedNull IGNORED_BACKENDS=JS
-// CHECK_TERNARY_OPERATOR_COUNT: function=upcast6 count=0 IGNORED_BACKENDS=JS
-// CHECK_IF_COUNT: function=upcast6 count=0 IGNORED_BACKENDS=JS
-// CHECK_BINOP_COUNT: function=instanceCheck6 count=0 symbol=instanceof IGNORED_BACKENDS=JS
-fun instanceCheck6() = getDerivedNull() is Base?
-
-fun box(): String {
-    assertSame(_derived, upcast1(), "upcast1()")
-    assertSame(_derived, upcast2(), "upcast2()")
-    assertSame(_derived, upcast3(), "upcast3()")
-    assertSame(_derived, upcast4(), "upcast4()")
-    failsClassCast("upcast5()") { upcast5() }
-    assertSame(null, upcast6(), "upcast6()")
-    assertEquals(6, counter)
-
-    counter = 0
-
-    assertSame(_derived, safeCast1(), "safeCast1()")
-    assertSame(_derived, safeCast2(), "safeCast2()")
-    assertSame(_derived, safeCast3(), "safeCast3()")
-    assertSame(_derived, safeCast4(), "safeCast4()")
-    assertSame(null,     safeCast5(), "safeCast5()")
-    assertSame(null,     safeCast6(), "safeCast6()")
-    assertEquals(6, counter)
-
-    counter = 0
-
-    assertTrue(instanceCheck1(), "instanceCheck1()")
-    assertTrue(instanceCheck2(), "instanceCheck2()")
-    assertTrue(instanceCheck3(), "instanceCheck3()")
-    assertTrue(instanceCheck4(), "instanceCheck4()")
-    assertFalse(instanceCheck5(), "instanceCheck5()")
-    assertTrue(instanceCheck6(), "instanceCheck6()")
-    assertEquals(6, counter)
-
-    return "OK"
-}
diff --git a/js/js.translator/testData/box/expression/cast/unsafeVarianceCast.kt b/js/js.translator/testData/box/expression/cast/unsafeVarianceCast.kt
new file mode 100644
index 00000000000..5f286bd4a5a
--- /dev/null
+++ b/js/js.translator/testData/box/expression/cast/unsafeVarianceCast.kt
@@ -0,0 +1,21 @@
+abstract class Foo<out E> {
+    abstract fun foo(element: @UnsafeVariance E): Boolean
+}
+
+class Bar<E : C> : Foo<E>() {
+    override fun foo(element: E): Boolean {
+        if (element !is C?) return false
+        return true
+    }
+}
+
+open class C
+
+open class D : C()
+
+fun box(): String {
+    val a = (object{})
+    val foo: Foo<Any?> = Bar<D>()
+    if (foo.foo(a as Any?)) return "fail"
+    return "OK"
+}
\ No newline at end of file
diff --git a/js/js.translator/testData/box/expression/function/overloadGeneric.kt b/js/js.translator/testData/box/expression/function/overloadGeneric.kt
new file mode 100644
index 00000000000..e397cfe8319
--- /dev/null
+++ b/js/js.translator/testData/box/expression/function/overloadGeneric.kt
@@ -0,0 +1,82 @@
+// KJS_WITH_FULL_RUNTIME
+
+class L<T>
+
+class A {
+    fun foo(a: L<Int>) = "Int"
+    fun foo(a: L<String>) = "String"
+    fun L<Int>.bar() = "Int2"
+    fun L<String>.bar() = "String2"
+}
+
+fun foo(a: L<Int>) = "Int"
+fun foo(a: L<String>) = "String"
+
+private class TestClass {
+    private val data = mutableListOf<List<Any>>()
+    fun withData(data: List<List<Any>>) = apply { this.data.addAll(data) }
+    fun withData(row: List<Any>) = apply {
+        data.add(row)
+    }
+
+    fun getCols(): Int {
+        return data.firstOrNull()?.size ?: return 0
+    }
+}
+
+object B {
+    fun baz(vararg v: B) = "[A]"
+
+    fun baz(vararg v: String) = "[S]"
+
+    fun baz(v: Array<String>) = "Array<String>"
+}
+
+class C<in T> {
+    fun bac(c: T): String {
+        return "T4"
+    }
+
+    fun bac(c: Int): String {
+        return "Int5"
+    }
+
+    fun bac(c: List<T>): String {
+        return "ListT4"
+    }
+
+    fun bac(c: List<Int>): String {
+        return "ListInt4"
+    }
+
+    fun bac(c: List<*>): String {
+        return "ListStar4"
+    }
+}
+
+fun box(): String {
+    if (A().foo(L<Int>()) != "Int") return "fail1"
+    A().apply {
+        if (L<Int>().bar() != "Int2") return "fail2"
+    }
+    if (foo(L<Int>()) != "Int") return "fail3"
+
+    val b = TestClass()
+    val data = mutableListOf<List<Any>>()
+    data.add(listOf("a", "b", "c"))
+    data.add(listOf("d", "e", "f"))
+    b.withData(data)
+    if (b.getCols() != 3) return "fail4"
+
+    if (B.baz(B) != "[A]") return "fail5"
+    if (B.baz("a") != "[S]") return "fail6"
+    if (B.baz(arrayOf("b")) != "Array<String>") return "fail7"
+
+    if(C<String>().bac("a") != "T4") return "fail8"
+    if(C<String>().bac(5) != "Int5") return "fail9"
+    if(C<String>().bac(listOf("a", "b")) != "ListT4") return "fail10"
+    if(C<String>().bac(listOf(5, 6)) != "ListInt4") return "fail11"
+    if(C<String>().bac(listOf(Any(), Any())) != "ListStar4") return "fail12"
+
+    return "OK"
+}
\ No newline at end of file
diff --git a/js/js.translator/testData/box/reified/isTNullable.kt b/js/js.translator/testData/box/reified/isTNullable.kt
index 34d5b6426dd..b3532f33f6d 100644
--- a/js/js.translator/testData/box/reified/isTNullable.kt
+++ b/js/js.translator/testData/box/reified/isTNullable.kt
@@ -3,8 +3,7 @@ package foo
 
 // CHECK_NOT_CALLED: isTypeOfOrNull
 // CHECK_NULLS_COUNT: function=box count=10 TARGET_BACKENDS=JS
-// CHECK_NULLS_COUNT: function=box count=0 IGNORED_BACKENDS=JS
-// CHECK_CONTAINS_NO_CALLS: box except=assertEquals;A IGNORED_BACKENDS=JS
+// CHECK_NULLS_COUNT: function=box count=6 IGNORED_BACKENDS=JS
 
 inline
 fun <reified T> Any?.isTypeOfOrNull() = this is T?
diff --git a/js/js.translator/testData/box/standardClasses/any.kt b/js/js.translator/testData/box/standardClasses/any.kt
index fb6fb192a90..7fb71144b36 100644
--- a/js/js.translator/testData/box/standardClasses/any.kt
+++ b/js/js.translator/testData/box/standardClasses/any.kt
@@ -1,5 +1,6 @@
 // EXPECTED_REACHABLE_NODES: 1285
 // CHECK_CALLED_IN_SCOPE: function=isType scope=box TARGET_BACKENDS=JS
+// CHECK_CALLED_IN_SCOPE: function=isObject scope=box IGNORED_BACKENDS=JS
 package foo
 
 class A : Any()
@@ -15,11 +16,9 @@ fun box(): String {
 
     if (arrayOf(1, 2, 3).asAny() !is Any) return "fail3"
 
-    if (testUtils.isLegacyBackend()) {
-        if (createNakedObject() is Any) return "fail4"
-    }
+    if (createNakedObject() is Any) return "fail4"
 
-    if (({  }).asAny() !is Any) return "fail5"
+    if (({ }).asAny() !is Any) return "fail5"
 
     if ((23).asAny() !is Any) return "fail6"
 
@@ -32,4 +31,4 @@ fun box(): String {
     return "OK"
 }
 
-fun createNakedObject(): Any? = js("Object.create(null)")
+fun createNakedObject(): Any? = js("Object.create(null)")
\ No newline at end of file
diff --git a/js/js.translator/testData/lineNumbers/whenIs.kt b/js/js.translator/testData/lineNumbers/whenIs.kt
index e742b06bf97..540a0d82b4d 100644
--- a/js/js.translator/testData/lineNumbers/whenIs.kt
+++ b/js/js.translator/testData/lineNumbers/whenIs.kt
@@ -14,4 +14,4 @@ open class A
 open class B : A()
 
 // LINES(JS):    1 10 2 2 2 2 3 3 4 4 5 5 6 6 8 8 12 * 14 14
-// LINES(JS_IR):          2 2     4 4 *                   14
+// LINES(JS_IR):          2 2 3   4 4 5   6 6 8 8 *    14
diff --git a/libraries/scripting/js-test/test/org/jetbrains/kotlin/scripting/repl/js/test/ReplTest.kt b/libraries/scripting/js-test/test/org/jetbrains/kotlin/scripting/repl/js/test/ReplTest.kt
index 5afad240a84..09ea7c378a6 100644
--- a/libraries/scripting/js-test/test/org/jetbrains/kotlin/scripting/repl/js/test/ReplTest.kt
+++ b/libraries/scripting/js-test/test/org/jetbrains/kotlin/scripting/repl/js/test/ReplTest.kt
@@ -122,6 +122,8 @@ abstract class AbstractReplTestRunner : TestCase() {
         Assert.assertEquals("OK", compileAndEval(lines))
     }
 
+    /* Ignore annotation doesn't work, so comment it
+    @Ignore("we use Object.assign inside type checks and nashorn does not support  it")
     @Test
     fun testInstanceOf() {
         val lines = listOf(
@@ -134,6 +136,7 @@ abstract class AbstractReplTestRunner : TestCase() {
         )
         Assert.assertEquals("truetrue", compileAndEval(lines))
     }
+     */
 
     @Test
     fun testScopes() {