diff --git a/js/js.libraries/src/generated/org.khronos.webgl.kt b/js/js.libraries/src/generated/org.khronos.webgl.kt
index b5ee523a10a..34e9181f2ed 100644
--- a/js/js.libraries/src/generated/org.khronos.webgl.kt
+++ b/js/js.libraries/src/generated/org.khronos.webgl.kt
@@ -567,10 +567,10 @@ native public open class ArrayBuffer(length: Int) : Transferable {
 }
 
 native public open class Int8Array : ArrayBufferView {
-    constructor(length: Int) : super()
-    constructor(array: Int8Array) : super()
-    constructor(array: Array<Byte>) : super()
-    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl) : super()
+    constructor(length: Int)
+    constructor(array: Int8Array)
+    constructor(array: Array<Byte>)
+    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl)
     var length: Int
         get() = noImpl
         set(value) = noImpl
@@ -595,10 +595,10 @@ native public open class Int8Array : ArrayBufferView {
 }
 
 native public open class Uint8Array : ArrayBufferView {
-    constructor(length: Int) : super()
-    constructor(array: Uint8Array) : super()
-    constructor(array: Array<Byte>) : super()
-    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl) : super()
+    constructor(length: Int)
+    constructor(array: Uint8Array)
+    constructor(array: Array<Byte>)
+    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl)
     var length: Int
         get() = noImpl
         set(value) = noImpl
@@ -623,10 +623,10 @@ native public open class Uint8Array : ArrayBufferView {
 }
 
 native public open class Uint8ClampedArray : ArrayBufferView {
-    constructor(length: Int) : super()
-    constructor(array: Uint8ClampedArray) : super()
-    constructor(array: Array<Byte>) : super()
-    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl) : super()
+    constructor(length: Int)
+    constructor(array: Uint8ClampedArray)
+    constructor(array: Array<Byte>)
+    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl)
     var length: Int
         get() = noImpl
         set(value) = noImpl
@@ -651,10 +651,10 @@ native public open class Uint8ClampedArray : ArrayBufferView {
 }
 
 native public open class Int16Array : ArrayBufferView {
-    constructor(length: Int) : super()
-    constructor(array: Int16Array) : super()
-    constructor(array: Array<Short>) : super()
-    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl) : super()
+    constructor(length: Int)
+    constructor(array: Int16Array)
+    constructor(array: Array<Short>)
+    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl)
     var length: Int
         get() = noImpl
         set(value) = noImpl
@@ -679,10 +679,10 @@ native public open class Int16Array : ArrayBufferView {
 }
 
 native public open class Uint16Array : ArrayBufferView {
-    constructor(length: Int) : super()
-    constructor(array: Uint16Array) : super()
-    constructor(array: Array<Short>) : super()
-    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl) : super()
+    constructor(length: Int)
+    constructor(array: Uint16Array)
+    constructor(array: Array<Short>)
+    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl)
     var length: Int
         get() = noImpl
         set(value) = noImpl
@@ -707,10 +707,10 @@ native public open class Uint16Array : ArrayBufferView {
 }
 
 native public open class Int32Array : ArrayBufferView {
-    constructor(length: Int) : super()
-    constructor(array: Int32Array) : super()
-    constructor(array: Array<Int>) : super()
-    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl) : super()
+    constructor(length: Int)
+    constructor(array: Int32Array)
+    constructor(array: Array<Int>)
+    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl)
     var length: Int
         get() = noImpl
         set(value) = noImpl
@@ -735,10 +735,10 @@ native public open class Int32Array : ArrayBufferView {
 }
 
 native public open class Uint32Array : ArrayBufferView {
-    constructor(length: Int) : super()
-    constructor(array: Uint32Array) : super()
-    constructor(array: Array<Int>) : super()
-    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl) : super()
+    constructor(length: Int)
+    constructor(array: Uint32Array)
+    constructor(array: Array<Int>)
+    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl)
     var length: Int
         get() = noImpl
         set(value) = noImpl
@@ -763,10 +763,10 @@ native public open class Uint32Array : ArrayBufferView {
 }
 
 native public open class Float32Array : ArrayBufferView {
-    constructor(length: Int) : super()
-    constructor(array: Float32Array) : super()
-    constructor(array: Array<Float>) : super()
-    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl) : super()
+    constructor(length: Int)
+    constructor(array: Float32Array)
+    constructor(array: Array<Float>)
+    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl)
     var length: Int
         get() = noImpl
         set(value) = noImpl
@@ -791,10 +791,10 @@ native public open class Float32Array : ArrayBufferView {
 }
 
 native public open class Float64Array : ArrayBufferView {
-    constructor(length: Int) : super()
-    constructor(array: Float64Array) : super()
-    constructor(array: Array<Double>) : super()
-    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl) : super()
+    constructor(length: Int)
+    constructor(array: Float64Array)
+    constructor(array: Array<Double>)
+    constructor(buffer: ArrayBuffer, byteOffset: Int = noImpl, length: Int = noImpl)
     var length: Int
         get() = noImpl
         set(value) = noImpl
diff --git a/js/js.libraries/src/generated/org.w3c.dom.kt b/js/js.libraries/src/generated/org.w3c.dom.kt
index f0a51271888..ea69ee53799 100644
--- a/js/js.libraries/src/generated/org.w3c.dom.kt
+++ b/js/js.libraries/src/generated/org.w3c.dom.kt
@@ -2996,8 +2996,8 @@ native public open class HitRegionOptions {
 }
 
 native public open class ImageData : ImageBitmapSource {
-    constructor(sw: Int, sh: Int) : super()
-    constructor(data: Uint8ClampedArray, sw: Int, sh: Int = noImpl) : super()
+    constructor(sw: Int, sh: Int)
+    constructor(data: Uint8ClampedArray, sw: Int, sh: Int = noImpl)
     var width: Int
         get() = noImpl
         set(value) = noImpl
@@ -5086,8 +5086,8 @@ native public open class DOMRectInit {
 }
 
 native public open class DOMQuad {
-    constructor(p1: DOMPointInit = noImpl, p2: DOMPointInit = noImpl, p3: DOMPointInit = noImpl, p4: DOMPointInit = noImpl) : super()
-    constructor(rect: DOMRectInit = noImpl) : super()
+    constructor(p1: DOMPointInit = noImpl, p2: DOMPointInit = noImpl, p3: DOMPointInit = noImpl, p4: DOMPointInit = noImpl)
+    constructor(rect: DOMRectInit = noImpl)
     var p1: DOMPoint
         get() = noImpl
         set(value) = noImpl
diff --git a/libraries/tools/idl2k/src/main/kotlin/gen.kt b/libraries/tools/idl2k/src/main/kotlin/gen.kt
index f773fc631d3..83836c8af86 100644
--- a/libraries/tools/idl2k/src/main/kotlin/gen.kt
+++ b/libraries/tools/idl2k/src/main/kotlin/gen.kt
@@ -83,7 +83,7 @@ private fun resolveDefinitionKind(repository: Repository, iface: InterfaceDefini
 private fun InterfaceDefinition.mapAttributes(repository: Repository) = attributes.map { generateAttribute(!dictionary, repository, it) }
 private fun InterfaceDefinition.mapOperations(repository: Repository) = operations.flatMap { generateFunctions(repository, it) }
 private fun Constant.mapConstant(repository : Repository) = GenerateAttribute(name, mapType(repository, type), value, false, true, false, false, true)
-private fun emptyConstructor() = ExtendedAttribute(null, "Constructor", emptyList())
+private val EMPTY_CONSTRUCTOR = ExtendedAttribute(null, "Constructor", emptyList())
 
 fun generateTrait(repository: Repository, iface: InterfaceDefinition): GenerateTraitOrClass {
     val superClasses = iface.superTypes
@@ -93,7 +93,7 @@ fun generateTrait(repository: Repository, iface: InterfaceDefinition): GenerateT
 
     assert(superClasses.size() <= 1) { "Type ${iface.name} should have one or zero super classes but found ${superClasses.map { it.name }}" }
     val superClass = superClasses.singleOrNull()
-    val superConstructor = superClass?.findConstructors()?.firstOrNull()
+    val superConstructor = superClass?.findConstructors()?.firstOrNull() ?: EMPTY_CONSTRUCTOR
 
     val declaredConstructors = iface.findConstructors()
     val entityKind = resolveDefinitionKind(repository, iface, declaredConstructors)
@@ -101,26 +101,27 @@ fun generateTrait(repository: Repository, iface: InterfaceDefinition): GenerateT
 
     val primaryConstructor = when {
         declaredConstructors.size() == 1 -> declaredConstructors.single()
-        declaredConstructors.isEmpty() && entityKind == GenerateDefinitionKind.CLASS -> emptyConstructor()
+        declaredConstructors.isEmpty() && entityKind == GenerateDefinitionKind.CLASS -> EMPTY_CONSTRUCTOR
         else -> declaredConstructors.firstOrNull { it.arguments.isEmpty() }
     }
     val secondaryConstructors = declaredConstructors.filter { it != primaryConstructor }
 
-    val primaryConstructorWithCall = if (primaryConstructor != null) {
-        val constructorAsFunction = generateConstructorAsFunction(repository, primaryConstructor)
+    val primaryConstructorWithCall = primaryConstructor?.let { constructor ->
+        val constructorAsFunction = generateConstructorAsFunction(repository, constructor)
         val superCall = when {
-            superClass != null -> superOrPrimaryConstructorCall(constructorAsFunction, superClass.name, superConstructor ?: emptyConstructor())
+            superClass != null -> superOrPrimaryConstructorCall(constructorAsFunction, superClass.name, superConstructor)
             else -> null
         }
 
-        ConstructorWithSuperTypeCall(constructorAsFunction, primaryConstructor, superCall)
-    } else null
+        ConstructorWithSuperTypeCall(constructorAsFunction, constructor, superCall)
+    }
 
     val secondaryConstructorsWithCall = secondaryConstructors.map { secondaryConstructor ->
         val constructorAsFunction = generateConstructorAsFunction(repository, secondaryConstructor)
         val initCall = when {
             primaryConstructorWithCall != null -> superOrPrimaryConstructorCall(constructorAsFunction, "this", primaryConstructorWithCall.constructorAttribute)
-            else -> superOrPrimaryConstructorCall(constructorAsFunction, "super", superConstructor ?: emptyConstructor())
+            superClass != null -> superOrPrimaryConstructorCall(constructorAsFunction, "super", superConstructor)
+            else -> null
         }
 
         ConstructorWithSuperTypeCall(constructorAsFunction, secondaryConstructor, initCall)
diff --git a/libraries/tools/idl2k/src/main/kotlin/render.kt b/libraries/tools/idl2k/src/main/kotlin/render.kt
index c3015f3e1f0..e7c142480d0 100644
--- a/libraries/tools/idl2k/src/main/kotlin/render.kt
+++ b/libraries/tools/idl2k/src/main/kotlin/render.kt
@@ -60,7 +60,7 @@ private fun Appendable.renderArgumentsDeclaration(args: List<GenerateAttribute>,
                     append(it.initializer.replaceWrongConstants(it.type))
                 }
             }
-        }.joinTo(this, ", ")
+        }.joinTo(this, ", ", "(", ")")
 
 private fun renderCall(call: GenerateFunctionCall) = "${call.name.replaceKeywords()}(${call.arguments.map { it.replaceKeywords() }.join(", ")})"
 
@@ -80,9 +80,9 @@ private fun Appendable.renderFunctionDeclaration(f: GenerateFunction, override:
     if (f.name in keywords) {
         append("native(\"${f.name}\") ")
     }
-    append("fun ${f.name.replaceKeywords()}(")
+    append("fun ${f.name.replaceKeywords()}")
     renderArgumentsDeclaration(f.arguments, override)
-    appendln("): ${f.returnType.render()} = noImpl")
+    appendln(": ${f.returnType.render()} = noImpl")
 }
 
 fun Appendable.render(allTypes: Map<String, GenerateTraitOrClass>, typeNamesToUnions: Map<String, List<String>>, iface: GenerateTraitOrClass, markerAnnotation: Boolean = false) {
@@ -100,17 +100,13 @@ fun Appendable.render(allTypes: Map<String, GenerateTraitOrClass>, typeNamesToUn
 
     append(iface.name)
     val primary = iface.primaryConstructor
-    if (primary != null) {
-        if (primary.constructor.arguments.isNotEmpty() || iface.secondaryConstructors.isNotEmpty()) {
-            append("(")
-            renderArgumentsDeclaration(primary.constructor.arguments.dynamicIfUnknownType(allTypes.keySet()), false)
-            append(")")
-        }
+    if (primary != null && (primary.constructor.arguments.isNotEmpty() || iface.secondaryConstructors.isNotEmpty())) {
+        renderArgumentsDeclaration(primary.constructor.arguments.dynamicIfUnknownType(allTypes.keySet()), false)
     }
 
     val superCallName = primary?.initTypeCall?.name
     val superTypesWithCalls =
-            listOf(primary?.initTypeCall).filterNotNull().map { renderCall(it) } +
+            (primary?.initTypeCall?.let { listOf(renderCall(it)) } ?: emptyList()) +
                     iface.superTypes.filter { it != superCallName && it in allSuperTypesNames } +
                     (typeNamesToUnions[iface.name] ?: emptyList())
 
@@ -122,9 +118,8 @@ fun Appendable.render(allTypes: Map<String, GenerateTraitOrClass>, typeNamesToUn
 
     iface.secondaryConstructors.forEach { secondary ->
         indent(1)
-        append("constructor(")
+        append("constructor")
         renderArgumentsDeclaration(secondary.constructor.arguments.dynamicIfUnknownType(allTypes.keySet()), false)
-        append(")")
 
         if (secondary.initTypeCall != null) {
             append(" : ")