diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/Dce.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/Dce.kt
index 4a2ec20fbd8..5acb009bc9d 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/Dce.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/Dce.kt
@@ -78,6 +78,8 @@ private fun removeUselessDeclarations(module: IrModuleFragment, usefulDeclaratio
                 process(declaration)
             }
 
+            // TODO bring back the primary constructor fix
+
             private fun process(container: IrDeclarationContainer) {
                 container.declarations.transformFlat { member ->
                     if (member !in usefulDeclarations) {
@@ -143,6 +145,7 @@ fun usefulDeclarations(roots: Iterable<IrDeclaration>, context: JsIrBackendConte
         while (queue.isNotEmpty()) {
             val declaration = queue.pollFirst()
 
+            // TODO remove?
             stageController.lazyLower(declaration)
 
             if (declaration is IrClass) {
@@ -188,6 +191,7 @@ fun usefulDeclarations(roots: Iterable<IrDeclaration>, context: JsIrBackendConte
                 else -> null
             }
 
+            // TODO remove?
             (body as? IrBody)?.let { stageController.lazyLower(it) }
 
             body?.acceptVoid(object : IrElementVisitorVoid {
@@ -285,6 +289,7 @@ fun usefulDeclarations(roots: Iterable<IrDeclaration>, context: JsIrBackendConte
                 }
             }
 
+            // TODO is this needed?
             for (declaration in ArrayList(klass.declarations)) {
                 // TODO this is a hack.
                 if (declaration is IrProperty) {
@@ -293,6 +298,7 @@ fun usefulDeclarations(roots: Iterable<IrDeclaration>, context: JsIrBackendConte
                 }
             }
 
+            // TODO deduplicate
             // Special hack for `IntrinsicsJs.kt` support
             if (klass.superTypes.any { it.isSuspendFunctionTypeOrSubtype() }) {
                 ArrayList(klass.declarations).forEach {
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt
index 790dc106f53..0f25f6edd64 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt
@@ -356,4 +356,5 @@ class JsIrBackendContext(
     }
 }
 
+// TODO: investigate if it could be removed
 fun <T> lazy2(fn: () -> T) = lazy { stageController.withInitialIr(fn) }
\ No newline at end of file
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
index a70f7ec0a77..ec7864922e7 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
@@ -641,8 +641,10 @@ val loweringList = listOf<Lowering>(
     validateIrAfterLowering
 )
 
+// TODO comment? Eliminate MouduleLowering's? Don't filter them here?
 val pirLowerings = loweringList.filter { it is DeclarationLowering || it is BodyLowering } + staticMembersLoweringPhase
 
+// TODO `fold` -> `reduce`
 val jsPhases = namedIrModulePhase(
     name = "IrModuleLowering",
     description = "IR module lowering",
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/MutableController.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/MutableController.kt
index 8322f489746..2c12539d482 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/MutableController.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/MutableController.kt
@@ -147,6 +147,7 @@ open class MutableController(val context: JsIrBackendContext, val lowerings: Lis
 
     override fun canModify(element: IrElement): Boolean {
         return true
+        // TODO fix and enable
 //        return !restricted || restrictedToDeclaration === element || element is IrPersistingElementBase<*> && element.createdOn == currentStage
     }
 
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/compiler.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/compiler.kt
index 43d81b2fd1a..bff0079cbd9 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/compiler.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/compiler.kt
@@ -97,6 +97,7 @@ fun compile(
 
         eliminateDeadDeclarations(moduleFragment, context, mainFunction)
 
+        // TODO investigate whether this is needed anymore
         stageController = object : StageController {
             override val currentStage: Int = controller.currentStage
         }
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrFileToJsTransformer.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrFileToJsTransformer.kt
index 9b2e305523e..38baf4a814a 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrFileToJsTransformer.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrFileToJsTransformer.kt
@@ -15,7 +15,7 @@ class IrFileToJsTransformer : BaseIrElementToJsNodeTransformer<JsBlock, JsGenera
         val fileContext = data.newDeclaration()
         val block = JsGlobalBlock()
 
-        ArrayList(declaration.declarations).forEach {
+        declaration.declarations.forEach {
             block.statements.add(it.accept(IrDeclarationToJsTransformer(), fileContext))
         }
 
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 ec00a5d9ffb..e4aa06507cf 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
@@ -199,8 +199,7 @@ class NameTables(
         }
 
         for (p in packages) {
-            // TODO
-            for (declaration in ArrayList(p.declarations)) {
+            for (declaration in p.declarations) {
                 acceptDeclaration(declaration)
             }
         }
@@ -333,6 +332,7 @@ class NameTables(
         val signature = fieldSignature(field)
         val name = memberNames.names[signature] ?: mappedNames[mapToKey(signature)]
 
+        // TODO investigate
         if (name == null) {
             return sanitizeName(field.name.asString()) + "__error"
         }
@@ -352,10 +352,13 @@ class NameTables(
         if (name == null && signature is ParameterTypeBasedSignature && signature.suggestedName.startsWith("invoke"))
             return signature.suggestedName
 
+        // TODO Add a compiler flag, which enables this behaviour
+        // TODO remove in DCE
         if (name == null) {
             return sanitizeName(function.name.asString()) + "__error" // TODO one case is a virtual method of an abstract class with no implementation
         }
 
+        // TODO report backend error
         require(name != null) {
             "Can't find name for member function ${function.render()}"
         }
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/PersistentApi.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/PersistentApi.kt
index ea1f4370cf5..a23964c9615 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/PersistentApi.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/PersistentApi.kt
@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.ir.expressions.IrBody
 // TODO make a IrDeclarationBase field? (requires IR factory)
 var stageController: StageController = object : StageController {}
 
+// TODO make a class
 interface StageController {
     val currentStage: Int get() = 0
 
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrDeclarationBase.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrDeclarationBase.kt
index bb44aa703b0..87b8444031b 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrDeclarationBase.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrDeclarationBase.kt
@@ -34,6 +34,7 @@ abstract class IrDeclarationBase<T : DeclarationCarrier<T>>(
 
     override var parentField: IrDeclarationParent? = null
 
+    // TODO reduce boilerplate
     override var parent: IrDeclarationParent
         get() = getCarrier().parentField ?: throw UninitializedPropertyAccessException("Parent not initialized: $this")
         set(p) {
@@ -84,6 +85,7 @@ abstract class IrPersistingElementBase<T : Carrier<T>>(
 
     var loweredUpTo = stageController.currentStage
 
+    // TODO Array<T>?
     private var values: Array<Any?>? = null
 
     val createdOn: Int = stageController.currentStage
@@ -120,6 +122,7 @@ abstract class IrPersistingElementBase<T : Carrier<T>>(
         }
     }
 
+    // TODO naming? e.g. `mutableCarrier`
     protected fun setCarrier(): T {
         val stage = stageController.currentStage
 
@@ -133,6 +136,7 @@ abstract class IrPersistingElementBase<T : Carrier<T>>(
             error("retrospective modification")
         }
 
+        // TODO move up? i.e. fast path
         if (stage == lastModified) {
             return this as T
         } else {
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/carriers/Carrier.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/carriers/Carrier.kt
index fe9586dfeb5..4e2457f5e34 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/carriers/Carrier.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/carriers/Carrier.kt
@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.ir.declarations.impl.carriers
 
+// TODO degenerify
+// TODO degenerify
 interface Carrier<in T : Carrier<T>> {
     val lastModified: Int
 
diff --git a/js/js.translator/testData/typescript-export/visibility/visibility.kt b/js/js.translator/testData/typescript-export/visibility/visibility.kt
index bd69c7e224e..6d63b345a2c 100644
--- a/js/js.translator/testData/typescript-export/visibility/visibility.kt
+++ b/js/js.translator/testData/typescript-export/visibility/visibility.kt
@@ -1,8 +1,10 @@
 // TARGET_BACKEND: JS_IR
-// SKIP_DCE_DRIVEN
 // CHECK_TYPESCRIPT_DECLARATIONS
 // RUN_PLAIN_BOX_FUNCTION
 
+// TODO fix statics export in DCE-driven mode
+// SKIP_DCE_DRIVEN
+
 @file:JsExport
 
 internal val internalVal = 10