diff --git a/compiler/testData/codegen/box/assert/alwaysEnable.kt b/compiler/testData/codegen/box/assert/alwaysEnable.kt
index 3c4db76e2b6..1f8152dec33 100644
--- a/compiler/testData/codegen/box/assert/alwaysEnable.kt
+++ b/compiler/testData/codegen/box/assert/alwaysEnable.kt
@@ -1,3 +1,4 @@
+// IGNORE_BACKEND: WASM
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 // IGNORE_BACKEND: JS
diff --git a/compiler/testData/codegen/box/casts/functions/isFunKBig.kt b/compiler/testData/codegen/box/casts/functions/isFunKBig.kt
index dee2a1d601c..2e0ab284ef3 100644
--- a/compiler/testData/codegen/box/casts/functions/isFunKBig.kt
+++ b/compiler/testData/codegen/box/casts/functions/isFunKBig.kt
@@ -40,11 +40,11 @@ abstract class TestFnBase(val type: String) {
     abstract fun testBad(x: Any)
 
     protected fun assertIs(x: Any, condition: Boolean) {
-        assert(condition) { "x is $type: failed for $x" }
+        require(condition) { "x is $type: failed for $x" }
     }
     
     protected fun assertIsNot(x: Any, condition: Boolean) {
-        assert(condition) { "x !is $type: failed for $x" }
+        require(condition) { "x !is $type: failed for $x" }
     }
 }
 
diff --git a/compiler/testData/codegen/box/casts/functions/reifiedIsFunKBig.kt b/compiler/testData/codegen/box/casts/functions/reifiedIsFunKBig.kt
index 6b15aed1f77..dc4ecfb1aea 100644
--- a/compiler/testData/codegen/box/casts/functions/reifiedIsFunKBig.kt
+++ b/compiler/testData/codegen/box/casts/functions/reifiedIsFunKBig.kt
@@ -43,7 +43,7 @@ inline fun <reified T> assertReifiedIs(x: Any, type: String) {
     catch (e: Throwable) {
         throw AssertionError("$x is $type: should not throw exceptions, got $e")
     }
-    assert(answer) { "$x is $type: failed" }
+    require(answer) { "$x is $type: failed" }
 }
 
 inline fun <reified T> assertReifiedIsNot(x: Any, type: String) {
@@ -54,7 +54,7 @@ inline fun <reified T> assertReifiedIsNot(x: Any, type: String) {
     catch (e: Throwable) {
         throw AssertionError("$x !is $type: should not throw exceptions, got $e")
     }
-    assert(answer) { "$x !is $type: failed" }
+    require(answer) { "$x !is $type: failed" }
 }
 
 abstract class TestFnBase(val type: String) {
diff --git a/compiler/testData/codegen/box/casts/functions/reifiedIsFunKSmall.kt b/compiler/testData/codegen/box/casts/functions/reifiedIsFunKSmall.kt
index 6c5234b6cd2..618af61c4fd 100644
--- a/compiler/testData/codegen/box/casts/functions/reifiedIsFunKSmall.kt
+++ b/compiler/testData/codegen/box/casts/functions/reifiedIsFunKSmall.kt
@@ -16,7 +16,7 @@ inline fun <reified T> assertReifiedIs(x: Any, type: String) {
     catch (e: Throwable) {
         throw AssertionError("$x is $type: should not throw exceptions, got $e")
     }
-    assert(answer) { "$x is $type: failed" }
+    require(answer) { "$x is $type: failed" }
 }
 
 inline fun <reified T> assertReifiedIsNot(x: Any, type: String) {
@@ -27,7 +27,7 @@ inline fun <reified T> assertReifiedIsNot(x: Any, type: String) {
     catch (e: Throwable) {
         throw AssertionError("$x !is $type: should not throw exceptions, got $e")
     }
-    assert(answer) { "$x !is $type: failed" }
+    require(answer) { "$x !is $type: failed" }
 }
 
 fun box(): String {
diff --git a/compiler/testData/codegen/box/casts/functions/safeAsFunKBig.kt b/compiler/testData/codegen/box/casts/functions/safeAsFunKBig.kt
index 0368ae2c5ce..a32418c6f37 100644
--- a/compiler/testData/codegen/box/casts/functions/safeAsFunKBig.kt
+++ b/compiler/testData/codegen/box/casts/functions/safeAsFunKBig.kt
@@ -38,7 +38,7 @@ val fns = arrayOf<Any>(::fn0, ::fn1, ::fn2, ::fn3, ::fn4, ::fn5, ::fn6, ::fn7, :
 inline fun safeAsReturnsNull(operation: String, cast: () -> Any?) {
     try {
         val x = cast()
-        assert(x == null) { "$operation: should return null, got $x" }
+        require(x == null) { "$operation: should return null, got $x" }
     }
     catch (e: Throwable) {
         throw AssertionError("$operation: should not throw exceptions, got $e")
@@ -48,7 +48,7 @@ inline fun safeAsReturnsNull(operation: String, cast: () -> Any?) {
 inline fun safeAsReturnsNonNull(operation: String, cast: () -> Any?) {
     try {
         val x = cast()
-        assert(x != null) { "$operation: should return non-null" }
+        require(x != null) { "$operation: should return non-null" }
     }
     catch (e: Throwable) {
         throw AssertionError("$operation: should not throw exceptions, got $e")
diff --git a/compiler/testData/codegen/box/casts/functions/safeAsFunKSmall.kt b/compiler/testData/codegen/box/casts/functions/safeAsFunKSmall.kt
index 67b3399f4cc..75774ca565c 100644
--- a/compiler/testData/codegen/box/casts/functions/safeAsFunKSmall.kt
+++ b/compiler/testData/codegen/box/casts/functions/safeAsFunKSmall.kt
@@ -11,7 +11,7 @@ fun fn1(x: Any) {}
 inline fun safeAsReturnsNull(operation: String, cast: () -> Any?) {
     try {
         val x = cast()
-        assert(x == null) { "$operation: should return null, got $x" }
+        require(x == null) { "$operation: should return null, got $x" }
     }
     catch (e: Throwable) {
         throw AssertionError("$operation: should not throw exceptions, got $e")
@@ -21,7 +21,7 @@ inline fun safeAsReturnsNull(operation: String, cast: () -> Any?) {
 inline fun safeAsReturnsNonNull(operation: String, cast: () -> Any?) {
     try {
         val x = cast()
-        assert(x != null) { "$operation: should return non-null" }
+        require(x != null) { "$operation: should return non-null" }
     }
     catch (e: Throwable) {
         throw AssertionError("$operation: should not throw exceptions, got $e")
diff --git a/compiler/testData/codegen/box/casts/mutableCollections/weirdMutableCasts.kt b/compiler/testData/codegen/box/casts/mutableCollections/weirdMutableCasts.kt
index 4b9b300dace..b45021ee6fa 100644
--- a/compiler/testData/codegen/box/casts/mutableCollections/weirdMutableCasts.kt
+++ b/compiler/testData/codegen/box/casts/mutableCollections/weirdMutableCasts.kt
@@ -1,8 +1,3 @@
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 // WITH_STDLIB
 
 fun unsupported(): Nothing = throw UnsupportedOperationException()
@@ -41,7 +36,7 @@ inline fun asSucceeds(operation: String, cast: () -> Unit) {
 inline fun safeAsReturnsNull(operation: String, cast: () -> Any?) {
     try {
         val x = cast()
-        assert(x == null) { "$operation: should return null, got $x" }
+        require(x == null) { "$operation: should return null, got $x" }
     }
     catch (e: Throwable) {
         throw AssertionError("$operation: should not throw exceptions, got $e")
@@ -51,7 +46,7 @@ inline fun safeAsReturnsNull(operation: String, cast: () -> Any?) {
 inline fun safeAsReturnsNonNull(operation: String, cast: () -> Any?) {
     try {
         val x = cast()
-        assert(x != null) { "$operation: should return non-null" }
+        require(x != null) { "$operation: should return non-null" }
     }
     catch (e: Throwable) {
         throw AssertionError("$operation: should not throw exceptions, got $e")
@@ -111,10 +106,10 @@ inline fun <reified T> reifiedSafeAsReturnsNull(x: Any?, operation: String) {
 fun box(): String {
     val w: Any = Weird()
 
-    assert(w is Iterator<*>) { "w is Iterator<*>" }
-    assert(w !is MutableIterator<*>) { "w !is MutableIterator<*>" }
-    assert(w is MutableIterable<*>) { "w is MutableIterable<*>" }
-    assert(w is MutableMap.MutableEntry<*, *>) { "w is MutableMap.MutableEntry<*, *>" }
+    require(w is Iterator<*>) { "w is Iterator<*>" }
+    require(w !is MutableIterator<*>) { "w !is MutableIterator<*>" }
+    require(w is MutableIterable<*>) { "w is MutableIterable<*>" }
+    require(w is MutableMap.MutableEntry<*, *>) { "w is MutableMap.MutableEntry<*, *>" }
 
     asSucceeds("w as Iterator<*>") { w as Iterator<*> }
     asFailsWithCCE("w as MutableIterator<*>") { w as MutableIterator<*> }
@@ -126,10 +121,10 @@ fun box(): String {
     safeAsReturnsNonNull("w as? MutableIterable<*>") { w as? MutableIterable<*> }
     safeAsReturnsNonNull("w as? MutableMap.MutableEntry<*, *>") { w as? MutableMap.MutableEntry<*, *> }
 
-    assert(reifiedIs<Iterator<*>>(w)) { "reifiedIs<Iterator<*>>(w)" }
-    assert(reifiedIsNot<MutableIterator<*>>(w)) { "reifiedIsNot<MutableIterator<*>>(w)" }
-    assert(reifiedIs<MutableIterable<*>>(w)) { "reifiedIs<MutableIterable<*>>(w)" }
-    assert(reifiedIs<MutableMap.MutableEntry<*, *>>(w)) { "reifiedIs<MutableMap.MutableEntry<*, *>>(w)" }
+    require(reifiedIs<Iterator<*>>(w)) { "reifiedIs<Iterator<*>>(w)" }
+    require(reifiedIsNot<MutableIterator<*>>(w)) { "reifiedIsNot<MutableIterator<*>>(w)" }
+    require(reifiedIs<MutableIterable<*>>(w)) { "reifiedIs<MutableIterable<*>>(w)" }
+    require(reifiedIs<MutableMap.MutableEntry<*, *>>(w)) { "reifiedIs<MutableMap.MutableEntry<*, *>>(w)" }
 
     reifiedAsSucceeds<Iterator<*>>(w, "reified w as Iterator<*>")
     reifiedAsFailsWithCCE<MutableIterator<*>>(w, "reified w as MutableIterator<*>")
diff --git a/compiler/testData/codegen/box/coroutines/doubleColonExpressionsGenerationInBuilderInference.kt b/compiler/testData/codegen/box/coroutines/doubleColonExpressionsGenerationInBuilderInference.kt
index ab90db54f11..4439fb5a7b5 100644
--- a/compiler/testData/codegen/box/coroutines/doubleColonExpressionsGenerationInBuilderInference.kt
+++ b/compiler/testData/codegen/box/coroutines/doubleColonExpressionsGenerationInBuilderInference.kt
@@ -1,5 +1,3 @@
-// IGNORE_BACKEND: JS, JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
 // WITH_STDLIB
 
 package a.b
@@ -22,7 +20,7 @@ fun test() {
     }
 
     val size = a.toList().size
-    assert(size == 5) { "actual size: $size"}
+    require(size == 5) { "actual size: $size"}
 }
 
 fun box(): String {
diff --git a/compiler/testData/codegen/box/ranges/safeCallRangeTo.kt b/compiler/testData/codegen/box/ranges/safeCallRangeTo.kt
index 103df9ba788..d0f5a6117c4 100644
--- a/compiler/testData/codegen/box/ranges/safeCallRangeTo.kt
+++ b/compiler/testData/codegen/box/ranges/safeCallRangeTo.kt
@@ -15,10 +15,10 @@ fun dougleRange(x: Double?, y: Double) = x?.rangeTo(y)
 
 inline fun <reified T, R> testSafeRange(x: T, y: T, expectStr: String, safeRange: (T?, T) -> R?) {
     val rNull = safeRange(null, y)
-    assert (rNull == null) { "${T::class.simpleName}: Expected: null, got $rNull" }
+    require (rNull == null) { "${T::class.simpleName}: Expected: null, got $rNull" }
 
     val rxy = safeRange(x, y)
-    assert (rxy?.toString() == expectStr) { "${T::class.simpleName}: Expected: $expectStr, got $rxy" }
+    require (rxy?.toString() == expectStr) { "${T::class.simpleName}: Expected: $expectStr, got $rxy" }
 }
 
 fun box(): String {
diff --git a/compiler/testData/codegen/box/regressions/kt2246.kt b/compiler/testData/codegen/box/regressions/kt2246.kt
index 044ba159714..73aafe18274 100644
--- a/compiler/testData/codegen/box/regressions/kt2246.kt
+++ b/compiler/testData/codegen/box/regressions/kt2246.kt
@@ -1,3 +1,4 @@
+// IGNORE_BACKEND: WASM
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
diff --git a/compiler/testData/codegen/box/reified/instanceof.kt b/compiler/testData/codegen/box/reified/instanceof.kt
index 2db9dae9d79..10ff3051655 100644
--- a/compiler/testData/codegen/box/reified/instanceof.kt
+++ b/compiler/testData/codegen/box/reified/instanceof.kt
@@ -1,8 +1,3 @@
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 // WITH_STDLIB
 
 inline fun<reified T> isinstance(x: Any?): Boolean {
@@ -10,9 +5,9 @@ inline fun<reified T> isinstance(x: Any?): Boolean {
 }
 
 fun box(): String {
-    assert(isinstance<String>("abc"))
-    assert(isinstance<Int>(1))
-    assert(!isinstance<Int>("abc"))
+    require(isinstance<String>("abc"))
+    require(isinstance<Int>(1))
+    require(!isinstance<Int>("abc"))
 
     return "OK"
 }
diff --git a/compiler/testData/codegen/box/reified/newArrayInt.kt b/compiler/testData/codegen/box/reified/newArrayInt.kt
index aed42bedd0d..c2c0f4806f2 100644
--- a/compiler/testData/codegen/box/reified/newArrayInt.kt
+++ b/compiler/testData/codegen/box/reified/newArrayInt.kt
@@ -1,8 +1,3 @@
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 // WITH_STDLIB
 
 inline fun<reified T> createArray(n: Int, crossinline block: () -> T): Array<T> {
@@ -13,6 +8,6 @@ fun box(): String {
 
     val x = createArray<Int>(5) { 3 }
 
-    assert(x.all { it == 3 })
+    require(x.all { it == 3 })
     return "OK"
 }
diff --git a/compiler/testData/codegen/box/reified/recursiveNewArray.kt b/compiler/testData/codegen/box/reified/recursiveNewArray.kt
index 518927b44dc..09e4a599912 100644
--- a/compiler/testData/codegen/box/reified/recursiveNewArray.kt
+++ b/compiler/testData/codegen/box/reified/recursiveNewArray.kt
@@ -1,8 +1,3 @@
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 // WITH_STDLIB
 
 inline fun<reified T> createArray(n: Int, crossinline block: () -> T): Array<T> {
@@ -18,6 +13,6 @@ inline fun<T1, T2, T3, T4, T5, T6, reified R> recursive(
 fun box(): String {
     val x = recursive<Int, Int, Int, Int, Int, Int, String>(){ "abc" }
 
-    assert(x.all { it == "abc" })
+    require(x.all { it == "abc" })
     return "OK"
 }
diff --git a/compiler/testData/codegen/box/reified/sameIndexRecursive.kt b/compiler/testData/codegen/box/reified/sameIndexRecursive.kt
index 0d53d587924..1ad0d30b9e0 100644
--- a/compiler/testData/codegen/box/reified/sameIndexRecursive.kt
+++ b/compiler/testData/codegen/box/reified/sameIndexRecursive.kt
@@ -1,8 +1,3 @@
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 // WITH_STDLIB
 
 inline fun<reified T1, reified T2> createArray(n: Int, crossinline block: () -> Pair<T1, T2>): Pair<Array<T1>, Array<T2>> {
@@ -19,9 +14,9 @@ fun box(): String {
     val y = createArray(5) { Pair(1, "test") }
     val x = recursive<Int, Int, Int, Int, Int, Int, String>(){ "abc" }
 
-    assert(y.first.all { it == 1 } )
-    assert(y.second.all { it == "test" })
-    assert(x.first.all { it == "abc" })
-    assert(x.second.all { it == "abc" })
+    require(y.first.all { it == 1 } )
+    require(y.second.all { it == "test" })
+    require(x.first.all { it == "abc" })
+    require(x.second.all { it == "abc" })
     return "OK"
 }
diff --git a/libraries/stdlib/wasm/src/kotlin/Assertions.kt b/libraries/stdlib/wasm/src/kotlin/Assertions.kt
index 680fdbcfc29..9053880755f 100644
--- a/libraries/stdlib/wasm/src/kotlin/Assertions.kt
+++ b/libraries/stdlib/wasm/src/kotlin/Assertions.kt
@@ -10,14 +10,14 @@ package kotlin
 /**
  * Throws an [AssertionError] if the [value] is false.
  */
-public fun assert(value: Boolean) {
+internal fun assert(value: Boolean) {
     assert(value) { "Assertion failed" }
 }
 
 /**
  * Throws an [AssertionError] calculated by [lazyMessage] if the [value] is false.
  */
-public fun assert(value: Boolean, lazyMessage: () -> Any) {
+internal fun assert(value: Boolean, lazyMessage: () -> Any) {
     if (!value) {
         val message = lazyMessage()
         throw AssertionError(message)