Hello, I am trying to use in Android's WebView a ...

# javascript

[Tristan]

Hello,

I am trying to use in Android's WebView a project using Kotlin/JS.

I am getting error method can't be invoked on a non-injected object

Looking on Google, I found this: https://bugs.chromium.org/p/chromium/issues/detail?id=514628

So I looked into the code generated, and indeed, we are not doing what they recommend. The code generated gives:

var tmp0_safe_receiver = Native.adOver;
return tmp0_safe_receiver == null ? null : tmp0_safe_receiver();

For

external object Native {
    val adOver: (() -> Unit)?
}

Native.adOver?.invoke()

According to the report, we should generate:

var tmp0_safe_receiver = Native.adOver.bind(Native);

Has it been reported yet? Is there a workaround (other than just use js("Native.adOver?.()"))

[ephemient]

I think what Kotlin generates matches Kotlin semantics

[diesieben07]

Yeah, but it is an external declaration, so Kotlin semantics are irrelvant. The problem here is really that the invoke call is fiction, in reality you are invoking adOver as a function, if it is present.
The correct code to preserve the correct receiver would be

var temp = Native.adOver;
return temp == null ? null : temp.call(Native)

Or Kotlin could just target modern Javascript (please...):
Native.adOver?.()

[ephemient]

that being said, if this is for a native bridge via webview:
- consider using createWebMessageChannel() instead of addJavascriptInterface()
- does it even need to be nullable? external object Native { fun adOver() }; Native.adOver() should generate the right code

[Tristan]

Thanks for your advice! I'll take a look to createWebMessageChannel. I was blindly following this https://developer.android.com/guide/webapps/webview

[diesieben07]

This should still be a YouTrack issue, as this is a bug

[ephemient]

it does feel strange to give

Native.adOver?.invoke()
Native.adOver?.let { it.invoke() }

different behavior in Kotlin, though, even if it is an external object

[ephemient]

it feels like the real interface is

external object Native {
    val adOver: (Native.() -> Unit)?
}

but that's not (currently) legal

[diesieben07]

That is a good point... but the 2nd syntax has a different meaning