Arrays and JSNI in J2CL

[Kirill Prazdnikov]

Hi, I've heard that mysterious J2CL does not support JSNI, good.

But how then the Float32Array is implemented ?
As far as I know, there is no JSIndexer-like (hello TeaVM) annotation in
JsInterop ?

Currently everyone is using JSNI llike

public static native float getF(Float32Array data, int i) /*-{

return data[i];
}-*/;

Thanks

[Thomas Broyer]

Post by Kirill Prazdnikov
Hi, I've heard that mysterious J2CL does not support JSNI, good.
But how then the Float32Array is implemented ?
As far as I know, there is no JSIndexer-like (hello TeaVM) annotation in
JsInterop ?
Currently everyone is using JSNI llike
public static native float getF(Float32Array data, int i) /*-{

return data[i];
}-*/;

Thanks

Don't worry, there's an alternative to JSNI. Its usage is meant to be much
smaller and exceptional than JSNI though.

Basically, you declare a method 'native' and give it a known name using
JsInterop (i.e. annotate it with @JsMethod), and then in a JS file you can
implement it, in "standard Closure way" (the class has the same name in JS
as in Java, so you assign a function to MyClass.prototype.getF).
That said, for this specific case, you'd probably better extend
JsArrayLike<Double> from jsinterop-base (this is what
elemental2.core.Float32Array does; knowing that java.lang.Double is
interchangeable with double as a representation of JS Number type, without
any overhead); or implement the method by casting to JsArrayLike<Double>:
public static float getF(Float32Array data, int i) {
return Js.asArrayLike(this).getAnyAt(i).asFloat();
}