In wasm how can i use showSaveFilePicker on `window`? I have imported `import kotlinx.browser.windo...

# webassembly

[Alex Styl]

In wasm how can i use showSaveFilePicker on window?

I have imported import kotlinx.browser.window but showSaveFilePicker() doesnt exist there

[Alex Styl]

I know that in the js target i could use window as dynamic, but I think wasm doesnt have dynamic

[Alex Styl]

I think i figured it out:

val window: WasmWindow = js("window")

external interface WasmWindow {
    fun showSaveFilePicker(): WasmFileSystemFileHandle
    fun showOpenFilePicker(options: FilePickerAcceptType? = definedExternally): Promise<JsArray<WasmFileSystemFileHandle>>
    fun alert(message: String)
    fun prompt(message: String, defaultText: String): String?
}

[turansky]

Do you support Chrome only?

[Alex Styl]

good catch. no i don't. the question still remains though, as im new to wasm and trying to understand how the target works

[turansky]

In common case it's better to write extensions for existed type (constant)

[turansky]

When methods will be stable you will receive warning on compilation and will remove redundant extensions

[Alex Styl]

I don't understand. Are you suggesting I do:

val window: WasmWindow = js("window")

fun WasmWindow.showSaveFilePicker(): WasmFileSystemFileHandle

etc

instead?

[Alex Styl]

can i do external extension functions?

[turansky]

fun Window.showSaveFilePicker(): FileSystemFileHandle = 
    js("this.showSaveFilePicker()")

?

[Dave]

this does not work for me?
wasm compile fails with js("...") calls

[Alex Styl]

I just tried the same thing on a new project and got Calls to 'js(code)' are not supported in function with extension receiver in Kotlin/Wasm.

[turansky]

Picker API added 😉
It will be available for both platforms in next Kotlin Wrappers release.

cc @Alex Styl

[turansky]

Released in Kotlin Wrappers 2025.7.8 ! 🎉🎉🎉

[turansky]

@Alex Styl do you need other experimental or Chrome only API? 😉