diff --git a/compiler/testData/codegen/boxWasmJsInterop/functionTypes.kt b/compiler/testData/codegen/boxWasmJsInterop/functionTypes.kt
index d531ac7812b..8162aa33f77 100644
--- a/compiler/testData/codegen/boxWasmJsInterop/functionTypes.kt
+++ b/compiler/testData/codegen/boxWasmJsInterop/functionTypes.kt
@@ -242,8 +242,9 @@ fun box(): String {
 }
 
 // TODO: Rewrite test to use module system
-@JsFun("() => { globalThis.main = wasmExports; }")
-external fun hackNonModuleExport()
+fun hackNonModuleExport() {
+    js("globalThis.main = wasmExports;")
+}
 
 fun main() {
     hackNonModuleExport()
diff --git a/compiler/testData/codegen/boxWasmJsInterop/jsExport.kt b/compiler/testData/codegen/boxWasmJsInterop/jsExport.kt
index 8bfd33cfd82..e9c0255ab9d 100644
--- a/compiler/testData/codegen/boxWasmJsInterop/jsExport.kt
+++ b/compiler/testData/codegen/boxWasmJsInterop/jsExport.kt
@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JS_IR, JS
 // WASM_FAILS_IN: SM
 // MODULE: main
 // FILE: externals.kt
@@ -29,8 +28,9 @@ fun box(): String = "OK"
 
 // TODO: Rewrite test to use module system
 
-@JsFun("() => { globalThis.main = wasmExports; }")
-external fun hackNonModuleExport()
+fun hackNonModuleExport() {
+    js("globalThis.main = wasmExports;")
+}
 
 fun main() {
     hackNonModuleExport()
diff --git a/compiler/testData/codegen/boxWasmJsInterop/jsToKotlinAdapters.kt b/compiler/testData/codegen/boxWasmJsInterop/jsToKotlinAdapters.kt
index e3d22b11d9e..b95eea9fcd6 100644
--- a/compiler/testData/codegen/boxWasmJsInterop/jsToKotlinAdapters.kt
+++ b/compiler/testData/codegen/boxWasmJsInterop/jsToKotlinAdapters.kt
@@ -11,17 +11,13 @@ inline fun checkNPE(body: () -> Unit) {
     check(throwed)
 }
 
-@JsFun("() => 'abc'")
-external fun notNullString(): String
+fun notNullString(): String = js("'abc'")
 
-@JsFun("() => null")
-external fun notNull2String(): String
+fun notNull2String(): String = js("null")
 
-@JsFun("() => 'abc'")
-external fun nullString(): String?
+fun nullString(): String? = js("'abc'")
 
-@JsFun("() => null")
-external fun null2String(): String?
+fun null2String(): String? = js("null")
 
 fun testString() {
     check(notNullString() == "abc")
@@ -32,17 +28,13 @@ fun testString() {
 
 external interface ExternRef
 
-@JsFun("() => 'abc'")
-external fun notNullExternRef(): ExternRef
+fun notNullExternRef(): ExternRef = js("'abc'")
 
-@JsFun("() => null")
-external fun notNull2ExternRef(): ExternRef
+fun notNull2ExternRef(): ExternRef = js("null")
 
-@JsFun("() => 'abc'")
-external fun nullExternRef(): ExternRef?
+fun nullExternRef(): ExternRef? = js("'abc'")
 
-@JsFun("() => null")
-external fun null2ExternRef(): ExternRef?
+fun null2ExternRef(): ExternRef? = js("null")
 
 
 fun testExterRef() {
@@ -54,17 +46,13 @@ fun testExterRef() {
 
 class DataRef
 
-@JsFun("(x) => x")
-external fun notNullDataRef(x: DataRef): DataRef
+fun notNullDataRef(x: DataRef): DataRef = js("x")
 
-@JsFun("(x) => null")
-external fun notNull2DataRef(x: DataRef): DataRef
+fun notNull2DataRef(x: DataRef): DataRef = js("null")
 
-@JsFun("(x) => x")
-external fun nullDataRef(x: DataRef): DataRef?
+fun nullDataRef(x: DataRef): DataRef? = js("x")
 
-@JsFun("(x) => null")
-external fun null2DataRef(x: DataRef): DataRef?
+fun null2DataRef(x: DataRef): DataRef? = js("null")
 
 fun testDataRef() {
     val dataRef = DataRef()
@@ -74,17 +62,13 @@ fun testDataRef() {
     check (null2DataRef(dataRef) == null)
 }
 
-@JsFun("() => 123")
-external fun notNullInt(): Int
+fun notNullInt(): Int = js("123")
 
-@JsFun("() => null")
-external fun notNull2Int(): Int
+fun notNull2Int(): Int = js("null")
 
-@JsFun("() => 123")
-external fun nullInt(): Int?
+fun nullInt(): Int? = js("123")
 
-@JsFun("() => null")
-external fun null2Int(): Int?
+fun null2Int(): Int? = js("null")
 
 fun testInt() {
     check(notNullInt() == 123)
@@ -93,17 +77,13 @@ fun testInt() {
     check(null2Int() == null)
 }
 
-@JsFun("() => true")
-external fun notNullBoolean(): Boolean
+fun notNullBoolean(): Boolean = js("true")
 
-@JsFun("() => null")
-external fun notNull2Boolean(): Boolean
+fun notNull2Boolean(): Boolean = js("null")
 
-@JsFun("() => true")
-external fun nullBoolean(): Boolean?
+fun nullBoolean(): Boolean? = js("true")
 
-@JsFun("() => null")
-external fun null2Boolean(): Boolean?
+fun null2Boolean(): Boolean? = js("null")
 
 fun testBoolean() {
     check(notNullBoolean() == true)
@@ -112,17 +92,13 @@ fun testBoolean() {
     check(null2Boolean() == null)
 }
 
-@JsFun("() => 123")
-external fun notNullShort(): Short
+fun notNullShort(): Short = js("123")
 
-@JsFun("() => null")
-external fun notNull2Short(): Short
+fun notNull2Short(): Short = js("null")
 
-@JsFun("() => 123")
-external fun nullShort(): Short?
+fun nullShort(): Short? = js("123")
 
-@JsFun("() => null")
-external fun null2Short(): Short?
+fun null2Short(): Short? = js("null")
 
 fun testShort() {
     check(notNullShort() == 123.toShort())
@@ -131,17 +107,13 @@ fun testShort() {
     check(null2Short() == null)
 }
 
-@JsFun("() => 123.5")
-external fun notNullFloat(): Float
+fun notNullFloat(): Float = js("123.5")
 
-@JsFun("() => null")
-external fun notNull2Float(): Float
+fun notNull2Float(): Float = js("null")
 
-@JsFun("() => 123.5")
-external fun nullFloat(): Float?
+fun nullFloat(): Float? = js("123.5")
 
-@JsFun("() => null")
-external fun null2Float(): Float?
+fun null2Float(): Float? = js("null")
 
 fun testFloat() {
     check(notNullFloat() == 123.5f)
@@ -151,17 +123,13 @@ fun testFloat() {
 }
 
 
-@JsFun("() => 123.5")
-external fun notNullNumber(): Number
+fun notNullNumber(): Number = js("123.5")
 
-@JsFun("() => null")
-external fun notNull2Number(): Number
+fun notNull2Number(): Number = js("null")
 
-@JsFun("() => 123.5")
-external fun nullNumber(): Number?
+fun nullNumber(): Number? = js("123.5")
 
-@JsFun("() => null")
-external fun null2Number(): Number?
+fun null2Number(): Number? = js("null")
 
 fun testNumber() {
     check(notNullNumber() == 123.5)
diff --git a/compiler/testData/codegen/boxWasmJsInterop/kotlinToJsAdapters.kt b/compiler/testData/codegen/boxWasmJsInterop/kotlinToJsAdapters.kt
index aa174ed9571..84eeb1cab1b 100644
--- a/compiler/testData/codegen/boxWasmJsInterop/kotlinToJsAdapters.kt
+++ b/compiler/testData/codegen/boxWasmJsInterop/kotlinToJsAdapters.kt
@@ -1,14 +1,16 @@
-// IGNORE_BACKEND: JS_IR, JS
 // WASM_FAILS_IN: SM
 
-@JsFun("(x) => { if (x !== 'abc') throw 'error' }")
-external fun notNullString(x: String)
+fun notNullString(x: String) {
+    js("if (x !== 'abc') throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== 'abc') throw 'error' }")
-external fun nullString(x: String?)
+fun nullString(x: String?) {
+    js("if (x !== 'abc') throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== null) throw 'error' }")
-external fun null2String(x: String?)
+fun null2String(x: String?) {
+    js("if (x !== null) throw 'error'")
+}
 
 fun testString() {
     notNullString("abc")
@@ -18,17 +20,20 @@ fun testString() {
 
 external interface ExternRef
 
-@JsFun("(x) => { if (x !== 'abc') throw 'error' }")
-external fun notNullExternRef(x: ExternRef)
+fun notNullExternRef(x: ExternRef) {
+    js("if (x !== 'abc') throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== 'abc') throw 'error' }")
-external fun nullExternRef(x: ExternRef?)
+fun nullExternRef(x: ExternRef?) {
+    js("if (x !== 'abc') throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== null) throw 'error' }")
-external fun null2ExternRef(x: ExternRef?)
+fun null2ExternRef(x: ExternRef?) {
+    js("if (x !== null) throw 'error'")
+}
 
-@JsFun("() => 'abc'")
-external fun getExternRef(): ExternRef
+fun getExternRef(): ExternRef =
+    js("'abc'")
 
 fun testExterRef() {
     val externRef = getExternRef()
@@ -39,14 +44,17 @@ fun testExterRef() {
 
 class DataRef
 
-@JsFun("(x, y) => { if (x === null) throw 'error' }")
-external fun notNullDataRef(x: DataRef)
+fun notNullDataRef(x: DataRef) {
+    js("if (x === null) throw 'error'")
+}
 
-@JsFun("(x, y) => { if (x === null) throw 'error' }")
-external fun nullDataRef(x: DataRef?)
+fun nullDataRef(x: DataRef?) {
+    js("if (x === null) throw 'error'")
+}
 
-@JsFun("(x, y) => { if (x !== null) throw 'error' }")
-external fun null2DataRef(x: DataRef?)
+fun null2DataRef(x: DataRef?) {
+    js("if (x !== null) throw 'error'")
+}
 
 fun testDataRef() {
     val dataRef = DataRef()
@@ -55,14 +63,17 @@ fun testDataRef() {
     null2DataRef(null)
 }
 
-@JsFun("(x) => { if (x !== 123) throw 'error' }")
-external fun notNullInt(x: Int)
+fun notNullInt(x: Int) {
+    js("if (x !== 123) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== 123) throw 'error' }")
-external fun nullInt(x: Int?)
+fun nullInt(x: Int?) {
+    js("if (x !== 123) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== null) throw 'error' }")
-external fun null2Int(x: Int?)
+fun null2Int(x: Int?) {
+    js("if (x !== null) throw 'error'")
+}
 
 fun testInt() {
     notNullInt(123)
@@ -70,14 +81,17 @@ fun testInt() {
     null2Int(null)
 }
 
-@JsFun("(x) => { if (x !== true) throw 'error' }")
-external fun notNullBoolean(x: Boolean)
+fun notNullBoolean(x: Boolean) {
+    js("if (x !== true) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== true) throw 'error' }")
-external fun nullBoolean(x: Boolean?)
+fun nullBoolean(x: Boolean?) {
+    js("if (x !== true) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== null) throw 'error' }")
-external fun null2Boolean(x: Boolean?)
+fun null2Boolean(x: Boolean?) {
+    js("if (x !== null) throw 'error'")
+}
 
 fun testBoolean() {
     notNullBoolean(true)
@@ -85,14 +99,17 @@ fun testBoolean() {
     null2Boolean(null)
 }
 
-@JsFun("(x) => { x == 123 }")
-external fun notNullShort(x: Short)
+fun notNullShort(x: Short) {
+    js("x == 123")
+}
 
-@JsFun("(x) => { if (x !== 123) throw 'error' }")
-external fun nullShort(x: Short?)
+fun nullShort(x: Short?) {
+    js("if (x !== 123) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== null) throw 'error' }")
-external fun null2Short(x: Short?)
+fun null2Short(x: Short?) {
+    js("if (x !== null) throw 'error'")
+}
 
 fun testShort() {
     notNullShort(123.toShort())
@@ -100,14 +117,17 @@ fun testShort() {
     null2Short(null)
 }
 
-@JsFun("(x) => { if (x !== 123.5) throw 'error' }")
-external fun notNullFloat(x: Float)
+fun notNullFloat(x: Float) {
+    js("if (x !== 123.5) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== 123.5) throw 'error' }")
-external fun nullFloat(x: Float?)
+fun nullFloat(x: Float?) {
+    js("if (x !== 123.5) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== null) throw 'error' }")
-external fun null2Float(x: Float?)
+fun null2Float(x: Float?) {
+    js("if (x !== null) throw 'error'")
+}
 
 fun testFloat() {
     notNullFloat(123.5f)
@@ -115,23 +135,29 @@ fun testFloat() {
     null2Float(null)
 }
 
-@JsFun("(x) => { if (x !== 123.5) throw 'error' }")
-external fun notNullNumber(x: Number)
+fun notNullNumber(x: Number) {
+    js("if (x !== 123.5) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== 123.5) throw 'error' }")
-external fun nullNumber(x: Number?)
+fun nullNumber(x: Number?) {
+    js("if (x !== 123.5) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== null) throw 'error' }")
-external fun null2Number(x: Number?)
+fun null2Number(x: Number?) {
+    js("if (x !== null) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== 123) throw 'error' }")
-external fun byte2Number(x: Number)
+fun byte2Number(x: Number) {
+    js("if (x !== 123) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== 123) throw 'error' }")
-external fun notNullByte2Number(x: Number?)
+fun notNullByte2Number(x: Number?) {
+    js("if (x !== 123) throw 'error'")
+}
 
-@JsFun("(x) => { if (x !== null) throw 'error' }")
-external fun nullByte2Number(x: Number?)
+fun nullByte2Number(x: Number?) {
+    js("if (x !== null) throw 'error'")
+}
 
 fun testNumber() {
     notNullNumber(123.5)
diff --git a/compiler/testData/codegen/boxWasmJsInterop/nullableExternRefs.kt b/compiler/testData/codegen/boxWasmJsInterop/nullableExternRefs.kt
index 793b8245461..de050009eba 100644
--- a/compiler/testData/codegen/boxWasmJsInterop/nullableExternRefs.kt
+++ b/compiler/testData/codegen/boxWasmJsInterop/nullableExternRefs.kt
@@ -19,23 +19,23 @@ fun assertFalse(x: Boolean) {
 
 external interface EI
 
-@JsFun("() => null")
-external fun getNull(): EI?
+fun getNull(): EI? =
+    js("null")
 
-@JsFun("() => undefined")
-external fun getUndefined(): EI?
+fun getUndefined(): EI? =
+    js("undefined")
 
-@JsFun("(ref) => ref === null")
-external fun isJsNull(ref: EI?): Boolean
+fun isJsNull(ref: EI?): Boolean =
+    js("ref === null")
 
-@JsFun("(ref) => ref === undefined")
-external fun isJsUndefined(ref: EI?): Boolean
+fun isJsUndefined(ref: EI?): Boolean =
+    js("ref === undefined")
 
-@JsFun("() => null")
-external fun getJsNullAsNonNullable(): EI
+fun getJsNullAsNonNullable(): EI =
+    js("null")
 
-@JsFun("() => undefined")
-external fun getJsUndefinedAsNonNullable(): EI
+fun getJsUndefinedAsNonNullable(): EI =
+    js("undefined")
 
 inline fun checkNPE(body: () -> Unit) {
     var throwed = false
diff --git a/libraries/kotlin.test/wasm/src/main/kotlin/kotlin/test/JasmineLikeAdapter.kt b/libraries/kotlin.test/wasm/src/main/kotlin/kotlin/test/JasmineLikeAdapter.kt
index 7e95e835a5e..378b88485dc 100644
--- a/libraries/kotlin.test/wasm/src/main/kotlin/kotlin/test/JasmineLikeAdapter.kt
+++ b/libraries/kotlin.test/wasm/src/main/kotlin/kotlin/test/JasmineLikeAdapter.kt
@@ -9,23 +9,25 @@ import kotlin.test.FrameworkAdapter
 import kotlin.js.Promise
 
 // Need to wrap into additional lambdas so that js launcher will work without Mocha or any other testing framework
-@JsFun("(name, fn) => describe(name, fn)")
-private external fun describe(name: String, fn: () -> Unit)
+private fun describe(name: String, fn: () -> Unit): Unit =
+    js("describe(name, fn)")
 
-@JsFun("(name, fn) => xdescribe(name, fn)")
-private external fun xdescribe(name: String, fn: () -> Unit)
+private fun xdescribe(name: String, fn: () -> Unit): Unit =
+    js("xdescribe(name, fn)")
 
-@JsFun("(name, fn) => it(name, fn)")
-private external fun it(name: String, fn: () -> Any?)
+private fun it(name: String, fn: () -> Any?): Unit =
+    js("it(name, fn)")
 
-@JsFun("(name, fn) => xit(name, fn)")
-private external fun xit(name: String, fn: () -> Any?)
+private fun xit(name: String, fn: () -> Any?): Unit =
+    js("xit(name, fn)")
 
-@JsFun("(e) => { throw e }")
-private external fun jsThrow(jsException: Dynamic)
+private fun jsThrow(jsException: Dynamic) {
+    js("throw e")
+}
 
-@JsFun("(message, stack) => { const e = new Error(); e.message = message; e.stack = stack; return e; }")
-private external fun throwableToJsError(message: String, stack: String): Dynamic
+private fun throwableToJsError(message: String, stack: String): Dynamic {
+    js("var e = new Error(); e.message = message; e.stack = stack; return e;")
+}
 
 private fun Throwable.toJsError(): Dynamic =
     throwableToJsError(message ?: "", stackTraceToString())
diff --git a/libraries/kotlin.test/wasm/src/main/kotlin/kotlin/test/TestApi.kt b/libraries/kotlin.test/wasm/src/main/kotlin/kotlin/test/TestApi.kt
index 79372f97692..321fc068aa5 100644
--- a/libraries/kotlin.test/wasm/src/main/kotlin/kotlin/test/TestApi.kt
+++ b/libraries/kotlin.test/wasm/src/main/kotlin/kotlin/test/TestApi.kt
@@ -39,8 +39,8 @@ internal fun test(name: String, ignored: Boolean, testFn: () -> Any?) {
 
 internal var currentAdapter: FrameworkAdapter? = null
 
-@JsFun("() => typeof describe === 'function' && typeof it === 'function'")
-private external fun isJasmine(): Boolean
+private fun isJasmine(): Boolean =
+    js("typeof describe === 'function' && typeof it === 'function'")
 
 internal fun adapter(): FrameworkAdapter {
     val result = currentAdapter ?: if (isJasmine()) JasmineLikeAdapter() else TeamcityAdapter()
diff --git a/libraries/stdlib/wasm/builtins/kotlin/Throwable.kt b/libraries/stdlib/wasm/builtins/kotlin/Throwable.kt
index fd14cb7f1ce..3ab31a26a69 100644
--- a/libraries/stdlib/wasm/builtins/kotlin/Throwable.kt
+++ b/libraries/stdlib/wasm/builtins/kotlin/Throwable.kt
@@ -40,5 +40,5 @@ public open class Throwable(open val message: String?, open val cause: kotlin.Th
     }
 }
 
-@JsFun("() => new Error().stack")
-private external fun captureStackTrace(): ExternalInterfaceType
\ No newline at end of file
+private fun captureStackTrace(): ExternalInterfaceType =
+    js("new Error().stack")
diff --git a/libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExceptionHelpers.kt b/libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExceptionHelpers.kt
index ec0c255537c..24acc198bcf 100644
--- a/libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExceptionHelpers.kt
+++ b/libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExceptionHelpers.kt
@@ -5,16 +5,16 @@
 
 package kotlin.wasm.internal
 
-@JsFun(
-"""(message, wasmTypeName, stack) => { 
-        const error = new Error();
-        error.message = message;
-        error.name = wasmTypeName;
-        error.stack = stack;
-        throw error;
-   }"""
-)
-private external fun throwJsError(message: String?, wasmTypeName: String?, stack: String): Nothing
+@Suppress("UNUSED_PARAMETER") // TODO: Remove after bootstrap update
+private fun throwJsError(message: String?, wasmTypeName: String?, stack: String): Nothing {
+    js("""
+    const error = new Error();
+    error.message = message;
+    error.name = wasmTypeName;
+    error.stack = stack;
+    throw error;
+    """)
+}
 
 internal fun throwAsJsException(t: Throwable): Nothing {
     throwJsError(t.message, t::class.simpleName, t.stackTraceToString())
diff --git a/libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExternalWrapper.kt b/libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExternalWrapper.kt
index 7997857f4dd..fbf62f22fa3 100644
--- a/libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExternalWrapper.kt
+++ b/libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExternalWrapper.kt
@@ -3,6 +3,8 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
+@file:Suppress("UNUSED_PARAMETER") // TODO: Remove after bootstrap update
+
 package kotlin.wasm.internal
 
 import kotlin.wasm.internal.reftypes.anyref
@@ -31,6 +33,7 @@ internal class JsExternalBox @WasmPrimitiveConstructor constructor(val ref: Exte
     }
 }
 
+@Suppress("DEPRECATION")
 //language=js
 @JsFun("""
 (() => {
@@ -85,41 +88,41 @@ return (obj) => {
 )
 private external fun externrefHashCode(ref: ExternalInterfaceType): Int
 
-@JsFun("ref => String(ref)")
-private external fun externrefToString(ref: ExternalInterfaceType): String
+private fun externrefToString(ref: ExternalInterfaceType): String =
+    js("String(ref)")
 
-@JsFun("ref => Number(ref)")
-private external fun externrefToInt(ref: ExternalInterfaceType): Int
+private fun externrefToInt(ref: ExternalInterfaceType): Int =
+    js("Number(ref)")
 
-@JsFun("ref => Number(ref)")
-private external fun externrefToLong(ref: ExternalInterfaceType): Long
+private fun externrefToLong(ref: ExternalInterfaceType): Long =
+    js("Number(ref)")
 
-@JsFun("ref => Boolean(ref)")
-private external fun externrefToBoolean(ref: ExternalInterfaceType): Boolean
+private fun externrefToBoolean(ref: ExternalInterfaceType): Boolean =
+    js("Boolean(ref)")
 
-@JsFun("ref => Number(ref)")
-private external fun externrefToFloat(ref: ExternalInterfaceType): Float
+private fun externrefToFloat(ref: ExternalInterfaceType): Float =
+    js("Number(ref)")
 
-@JsFun("ref => Number(ref)")
-private external fun externrefToDouble(ref: ExternalInterfaceType): Double
+private fun externrefToDouble(ref: ExternalInterfaceType): Double =
+    js("Number(ref)")
 
-@JsFun("x => x")
-private external fun intToExternref(x: Int): ExternalInterfaceType
+private fun intToExternref(x: Int): ExternalInterfaceType =
+    js("x")
 
-@JsFun("x => x")
-private external fun longToExternref(x: Long): ExternalInterfaceType
+private fun longToExternref(x: Long): ExternalInterfaceType =
+    js("x")
 
-@JsFun("x => x")
-private external fun booleanToExternref(x: Boolean): ExternalInterfaceType
+private fun booleanToExternref(x: Boolean): ExternalInterfaceType =
+    js("x")
 
-@JsFun("x => x")
-private external fun floatToExternref(x: Float): ExternalInterfaceType
+private fun floatToExternref(x: Float): ExternalInterfaceType =
+    js("x")
 
-@JsFun("x => x")
-private external fun doubleToExternref(x: Double): ExternalInterfaceType
+private fun doubleToExternref(x: Double): ExternalInterfaceType =
+    js("x")
 
-@JsFun("(lhs, rhs) => lhs === rhs")
-private external fun externrefEquals(lhs: ExternalInterfaceType, rhs: ExternalInterfaceType): Boolean
+private fun externrefEquals(lhs: ExternalInterfaceType, rhs: ExternalInterfaceType): Boolean =
+    js("lhs === rhs")
 
 private external fun tryGetOrSetExternrefBox(ref: ExternalInterfaceType, ifNotCached: JsExternalBox): JsExternalBox?
 
@@ -136,8 +139,8 @@ private fun ExternalInterfaceType.externAsWasmAnyref(): anyref =
 private fun Any.asWasmExternRef(): ExternalInterfaceType =
     implementedAsIntrinsic
 
-@JsFun("(ref) => ref == null")
-internal external fun isNullish(ref: ExternalInterfaceType?): Boolean
+internal fun isNullish(ref: ExternalInterfaceType?): Boolean =
+    js("ref == null")
 
 @Suppress("UNUSED_PARAMETER")
 @ExcludedFromCodegen
@@ -179,18 +182,18 @@ internal fun anyToExternRef(x: Any): ExternalInterfaceType {
         x.asWasmExternRef()
 }
 
-@JsFun("x => x.length")
-internal external fun stringLength(x: ExternalInterfaceType): Int
+internal fun stringLength(x: ExternalInterfaceType): Int =
+    js("x.length")
 
 // kotlin string to js string export
 // TODO Uint16Array may work with byte endian different with Wasm (i.e. little endian)
-@JsFun("""(address, length, prefix) => {
+internal fun importStringFromWasm(address: Int, length: Int, prefix: ExternalInterfaceType?): ExternalInterfaceType {
+    js("""
     const mem16 = new Uint16Array(wasmExports.memory.buffer, address, length);
     const str = String.fromCharCode.apply(null, mem16);
     return (prefix == null) ? str : prefix + str;
+    """)
 }
-""")
-internal external fun importStringFromWasm(address: Int, length: Int, prefix: ExternalInterfaceType?): ExternalInterfaceType
 
 internal fun kotlinToJsStringAdapter(x: String?): ExternalInterfaceType? {
     // Using nullable String to represent default value
@@ -224,21 +227,18 @@ internal fun jsCheckIsNullOrUndefinedAdapter(x: ExternalInterfaceType?): Externa
 
 // js string to kotlin string import
 // TODO Uint16Array may work with byte endian different with Wasm (i.e. little endian)
-//language=js
-@JsFun(
-    """ (src, srcOffset, srcLength, dstAddr) => {
-        const mem16 = new Uint16Array(wasmExports.memory.buffer, dstAddr, srcLength);
-        let arrayIndex = 0;
-        let srcIndex = srcOffset;
-        while (arrayIndex < srcLength) {
-            mem16.set([src.charCodeAt(srcIndex)], arrayIndex);
-            srcIndex++;
-            arrayIndex++;
-        }
-    }
-"""
-)
-internal external fun jsExportStringToWasm(src: ExternalInterfaceType, srcOffset: Int, srcLength: Int, dstAddr: Int)
+internal fun jsExportStringToWasm(src: ExternalInterfaceType, srcOffset: Int, srcLength: Int, dstAddr: Int) {
+    js("""
+    const mem16 = new Uint16Array(wasmExports.memory.buffer, dstAddr, srcLength);
+    let arrayIndex = 0;
+    let srcIndex = srcOffset;
+    while (arrayIndex < srcLength) {
+        mem16.set([src.charCodeAt(srcIndex)], arrayIndex);
+        srcIndex++;
+        arrayIndex++;
+    }     
+    """)
+}
 
 private const val STRING_INTEROP_MEM_BUFFER_SIZE = 65_536 // 1 page 4KiB
 
@@ -269,14 +269,14 @@ internal fun jsToKotlinStringAdapter(x: ExternalInterfaceType): String {
 }
 
 
-@JsFun("() => ''")
-private external fun getJsEmptyString(): ExternalInterfaceType
+private fun getJsEmptyString(): ExternalInterfaceType =
+    js("''")
 
-@JsFun("() => true")
-private external fun getJsTrue(): ExternalInterfaceType
+private fun getJsTrue(): ExternalInterfaceType =
+    js("true")
 
-@JsFun("() => false")
-private external fun getJsFalse(): ExternalInterfaceType
+private fun getJsFalse(): ExternalInterfaceType =
+    js("false")
 
 private val jsEmptyString by lazy(::getJsEmptyString)
 private val jsTrue by lazy(::getJsTrue)
@@ -335,8 +335,9 @@ internal fun kotlinShortToExternRefAdapter(x: Short): ExternalInterfaceType =
 internal fun kotlinCharToExternRefAdapter(x: Char): ExternalInterfaceType =
     intToExternref(x.toInt())
 
-@JsFun("() => []")
-internal external fun newJsArray(): ExternalInterfaceType
+internal fun newJsArray(): ExternalInterfaceType =
+    js("[]")
 
-@JsFun("(array, element) => { array.push(element); }")
-internal external fun jsArrayPush(array: ExternalInterfaceType, element: ExternalInterfaceType)
\ No newline at end of file
+internal fun jsArrayPush(array: ExternalInterfaceType, element: ExternalInterfaceType) {
+    js("array.push(element);")
+}
diff --git a/libraries/stdlib/wasm/src/kotlin/Dynamic.kt b/libraries/stdlib/wasm/src/kotlin/Dynamic.kt
index 22552f18965..b19d02f93fb 100644
--- a/libraries/stdlib/wasm/src/kotlin/Dynamic.kt
+++ b/libraries/stdlib/wasm/src/kotlin/Dynamic.kt
@@ -3,87 +3,89 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
+@file:Suppress("UNUSED_PARAMETER") // TODO: Remove after bootstrap update
+
 package kotlin.js
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetBoolean(obj: Dynamic, index: String, value: Boolean)
+internal fun dynamicSetBoolean(obj: Dynamic, index: String, value: Boolean): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetByte(obj: Dynamic, index: String, value: Byte)
+internal fun dynamicSetByte(obj: Dynamic, index: String, value: Byte): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetShort(obj: Dynamic, index: String, value: Short)
+internal fun dynamicSetShort(obj: Dynamic, index: String, value: Short): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetChar(obj: Dynamic, index: String, value: Char)
+internal fun dynamicSetChar(obj: Dynamic, index: String, value: Char): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetInt(obj: Dynamic, index: String, value: Int)
+internal fun dynamicSetInt(obj: Dynamic, index: String, value: Int): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetLong(obj: Dynamic, index: String, value: Long)
+internal fun dynamicSetLong(obj: Dynamic, index: String, value: Long): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetFloat(obj: Dynamic, index: String, value: Float)
+internal fun dynamicSetFloat(obj: Dynamic, index: String, value: Float): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetDouble(obj: Dynamic, index: String, value: Double)
+internal fun dynamicSetDouble(obj: Dynamic, index: String, value: Double): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetString(obj: Dynamic, index: String, value: String?)
+internal fun dynamicSetString(obj: Dynamic, index: String, value: String?): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index, value) => obj[index] = value")
-internal external fun dynamicSetAny(obj: Dynamic, index: String, value: Any?)
+internal fun dynamicSetAny(obj: Dynamic, index: String, value: Any?): Unit =
+    js("obj[index] = value")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetBoolean(obj: Dynamic, index: String): Boolean
+internal fun dynamicGetBoolean(obj: Dynamic, index: String): Boolean =
+    js("obj[index]")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetByte(obj: Dynamic, index: String): Byte
+internal fun dynamicGetByte(obj: Dynamic, index: String): Byte =
+    js("obj[index]")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetShort(obj: Dynamic, index: String): Short
+internal fun dynamicGetShort(obj: Dynamic, index: String): Short =
+    js("obj[index]")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetChar(obj: Dynamic, index: String): Char
+internal fun dynamicGetChar(obj: Dynamic, index: String): Char =
+    js("obj[index]")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetInt(obj: Dynamic, index: String): Int
+internal fun dynamicGetInt(obj: Dynamic, index: String): Int =
+    js("obj[index]")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetLong(obj: Dynamic, index: String): Long
+internal fun dynamicGetLong(obj: Dynamic, index: String): Long =
+    js("obj[index]")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetFloat(obj: Dynamic, index: String): Float
+internal fun dynamicGetFloat(obj: Dynamic, index: String): Float =
+    js("obj[index]")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetDouble(obj: Dynamic, index: String): Double
+internal fun dynamicGetDouble(obj: Dynamic, index: String): Double =
+    js("obj[index]")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetString(obj: Dynamic, index: String): String?
+internal fun dynamicGetString(obj: Dynamic, index: String): String? =
+    js("obj[index]")
 
 @PublishedApi
-@JsFun("(obj, index) => obj[index]")
-internal external fun dynamicGetAny(obj: Dynamic, index: String): Any?
+internal fun dynamicGetAny(obj: Dynamic, index: String): Any? =
+    js("obj[index]")
 
 @PublishedApi
 internal fun Dynamic.getBoolean(index: String): Boolean = dynamicGetBoolean(this, index)
@@ -184,14 +186,12 @@ operator fun Dynamic.set(index: Int, value: Any?) {
     this[index.toString()] = value
 }
 
-@JsFun("(x) => x")
-private external fun <T> unsafeCastJs(x: String): Dynamic
+private fun <T> unsafeCastJs(x: String): Dynamic = js("x")
 
 @Suppress("UNCHECKED_CAST")
 fun <T> String.unsafeCast(): T = unsafeCastJs<T>(this) as T
 
-@JsFun("(x) => x")
-private external fun <T> unsafeCastJs(x: Boolean): Dynamic
+private fun <T> unsafeCastJs(x: Boolean): Dynamic = js("x")
 
 /**
  * Reinterprets boolean value as a value of the specified type [T] without any actual type checking.
@@ -210,10 +210,12 @@ fun <T> Nothing?.unsafeCast(): Dynamic? = null
 @Suppress("UNCHECKED_CAST")
 fun <T> Dynamic.unsafeCast(): T = this as T
 
-@JsFun("e => { throw e; }")
-private external fun jsThrow(e: Dynamic)
+private fun jsThrow(e: Dynamic) {
+    js("throw e;")
+}
 
-@JsFun("""(f) => {
+private fun jsCatch(f: () -> Unit): Dynamic? {
+    js("""
     let result = null;
     try { 
         f();
@@ -221,8 +223,8 @@ private external fun jsThrow(e: Dynamic)
        result = e;
     }
     return result;
-}""")
-private external fun jsCatch(f: () -> Unit): Dynamic?
+    """)
+}
 
 /**
  * For a Dynamic value caught in JS, returns the corresponding [Throwable]
diff --git a/libraries/stdlib/wasm/src/kotlin/io.kt b/libraries/stdlib/wasm/src/kotlin/io.kt
index ac34163de4b..4a058a9475f 100644
--- a/libraries/stdlib/wasm/src/kotlin/io.kt
+++ b/libraries/stdlib/wasm/src/kotlin/io.kt
@@ -3,18 +3,20 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
+@file:Suppress("UNUSED_PARAMETER") // TODO: Remove after bootstrap update
+
 package kotlin.io
 
 import kotlin.wasm.internal.*
 
-@JsFun("(error) => console.error(error)")
-internal external fun printError(error: String?): Unit
+internal fun printError(error: String?): Unit =
+    js("console.error(error)")
 
-@JsFun("(message) => console.log(message)")
-private external fun printlnImpl(message: String?): Unit
+private fun printlnImpl(message: String?): Unit =
+    js("console.log(message)")
 
-@JsFun("(message) => typeof write !== 'undefined' ? write(message) : console.log(message)")
-private external fun printImpl(message: String?): Unit
+private fun printImpl(message: String?): Unit =
+    js("typeof write !== 'undefined' ? write(message) : console.log(message)")
 
 /** Prints the line separator to the standard output stream. */
 public actual fun println() {
diff --git a/libraries/stdlib/wasm/src/kotlin/random/PlatformRandom.kt b/libraries/stdlib/wasm/src/kotlin/random/PlatformRandom.kt
index 5a320d56e75..149f9873099 100644
--- a/libraries/stdlib/wasm/src/kotlin/random/PlatformRandom.kt
+++ b/libraries/stdlib/wasm/src/kotlin/random/PlatformRandom.kt
@@ -5,8 +5,8 @@
 
 package kotlin.random
 
-@JsFun("() => ((Math.random() * Math.pow(2, 32)) | 0)")
-private external fun initialSeed(): Int
+private fun initialSeed(): Int =
+    js("((Math.random() * Math.pow(2, 32)) | 0)")
 
 internal actual fun defaultPlatformRandom(): Random =
     Random(initialSeed())
diff --git a/libraries/stdlib/wasm/src/kotlin/time/Duration.kt b/libraries/stdlib/wasm/src/kotlin/time/Duration.kt
index c35a207f63e..03edf9e9b48 100644
--- a/libraries/stdlib/wasm/src/kotlin/time/Duration.kt
+++ b/libraries/stdlib/wasm/src/kotlin/time/Duration.kt
@@ -3,17 +3,19 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
+@file:Suppress("UNUSED_PARAMETER") // TODO: Remove after bootstrap update
+
 package kotlin.time
 
 import kotlin.math.*
 
 internal actual inline val durationAssertionsEnabled: Boolean get() = true
 
-@JsFun("(value, decimals) => value.toFixed(decimals)")
-private external fun toFixed(value: Double, decimals: Int): String
+private fun toFixed(value: Double, decimals: Int): String =
+    js("value.toFixed(decimals)")
 
-@JsFun("(value, decimals) => value.toPrecision(decimals)")
-private external fun toPrecision(value: Double, decimals: Int): String
+private fun toPrecision(value: Double, decimals: Int): String =
+    js("value.toPrecision(decimals)")
 
 internal actual fun formatToExactDecimals(value: Double, decimals: Int): String {
     val rounded = if (decimals == 0) {
@@ -34,5 +36,5 @@ internal actual fun formatToExactDecimals(value: Double, decimals: Int): String
     }
 }
 
-@JsFun("(value, decimals) => value.toLocaleString(\"en-us\", ({\"maximumFractionDigits\": decimals}))")
-external internal actual fun formatUpToDecimals(value: Double, decimals: Int): String
\ No newline at end of file
+internal actual fun formatUpToDecimals(value: Double, decimals: Int): String =
+    js("(value, decimals) => value.toLocaleString(\"en-us\", ({\"maximumFractionDigits\": decimals}))")
\ No newline at end of file
diff --git a/libraries/stdlib/wasm/src/kotlin/time/TimeSources.kt b/libraries/stdlib/wasm/src/kotlin/time/TimeSources.kt
index 68060b4d470..bf61e721b81 100644
--- a/libraries/stdlib/wasm/src/kotlin/time/TimeSources.kt
+++ b/libraries/stdlib/wasm/src/kotlin/time/TimeSources.kt
@@ -3,20 +3,22 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
+@file:Suppress("UNUSED_PARAMETER") // TODO: Remove after bootstrap advance
+
 package kotlin.time
 
 import kotlin.wasm.internal.ExternalInterfaceType
 import kotlin.time.TimeSource.Monotonic.ValueTimeMark
 import kotlin.time.Duration.Companion.milliseconds
 
-@JsFun("() => typeof globalThis !== 'undefined' && typeof globalThis.performance !== 'undefined' ? globalThis.performance : null")
-private external fun tryGetPerformance(): ExternalInterfaceType?
+private fun tryGetPerformance(): ExternalInterfaceType? =
+    js("typeof globalThis !== 'undefined' && typeof globalThis.performance !== 'undefined' ? globalThis.performance : null")
 
-@JsFun("(performance) => performance.now()")
-private external fun getPerformanceNow(performance: ExternalInterfaceType): Double
+private fun getPerformanceNow(performance: ExternalInterfaceType): Double =
+    js("performance.now()")
 
-@JsFun("() => Date.now()")
-private external fun dateNow(): Double
+private fun dateNow(): Double =
+    js("Date.now()")
 
 @SinceKotlin("1.3")
 @ExperimentalTime
diff --git a/libraries/stdlib/wasm/src/kotlin/w3cSupport.kt b/libraries/stdlib/wasm/src/kotlin/w3cSupport.kt
index 0d7e3982d22..11966e23aab 100644
--- a/libraries/stdlib/wasm/src/kotlin/w3cSupport.kt
+++ b/libraries/stdlib/wasm/src/kotlin/w3cSupport.kt
@@ -9,5 +9,5 @@ package kotlin.js
 internal val undefined: Nothing? = null
 
 @PublishedApi
-@JsFun("() => ({})")
-internal external fun newJsObject(): Dynamic
\ No newline at end of file
+internal fun newJsObject(): Dynamic =
+    js("({})")
diff --git a/libraries/stdlib/wasm/test/js/AsyncTest.kt b/libraries/stdlib/wasm/test/js/AsyncTest.kt
index e8f6563e709..2bc10248b9a 100644
--- a/libraries/stdlib/wasm/test/js/AsyncTest.kt
+++ b/libraries/stdlib/wasm/test/js/AsyncTest.kt
@@ -3,11 +3,11 @@ package test.js
 import kotlin.js.*
 import kotlin.test.*
 
-@JsFun("async () => 'foo'")
-internal external fun jsAsyncFoo(): Promise<Dynamic?>
+internal fun jsAsyncFoo(): Promise<Dynamic?> =
+    js("(async () => 'foo')()")
 
-@JsFun("() => 'foo'")
-internal external fun jsFoo(): Dynamic
+internal fun jsFoo(): Dynamic =
+    js("'foo'")
 
 var state: Dynamic? = null
 
diff --git a/libraries/stdlib/wasm/test/unsafe/MemoryAllocationTest.kt b/libraries/stdlib/wasm/test/unsafe/MemoryAllocationTest.kt
index 94836072550..d4563cca4c6 100644
--- a/libraries/stdlib/wasm/test/unsafe/MemoryAllocationTest.kt
+++ b/libraries/stdlib/wasm/test/unsafe/MemoryAllocationTest.kt
@@ -3,8 +3,8 @@ package test.wasm.unsafe
 import kotlin.wasm.unsafe.*
 import kotlin.test.*
 
-@JsFun("(a, b) => a + b")
-private external fun jsConcatStrings(a: String, b: String): String
+private fun jsConcatStrings(a: String, b: String): String =
+    js("a + b")
 
 @OptIn(UnsafeWasmMemoryApi::class)
 class MemoryAllocationTest {