How to call a global JS method?

[faveoled]

Trying to write a binding to a global JS method with this code:

@JsType(isNative = true, namespace = GLOBAL)
public class Globals {
    @JsMethod(name = "addEventListener", namespace = GLOBAL)
    public static native void addEventListener(String type, EventListener listener);

}

JS exports:

var addEventListener = function (type, listener) {};

Getting this error:

[ERROR] app:app:1.0-SNAPSHOT/optimized_js: /home/user/Dev/Java/j2cl-proxy-workers/target/gwt3BuildCache/0.20/app-app-1.0-SNAPSHOT/fdf0ed43cf36cb92a1a3baa3a34e7934-transpiled_js/results/app/Globals$$Overlay.impl.java.js:13:29: ERROR - [JSC_UNDEFINED_VARIABLE] variable Globals is undeclared
  return instance instanceof Globals;
                             ^^^^^^^

Any ideas on how to fix the binding?

[niloc132]

The issue here is the same as in #227 - you're code says "there's a class in JS called Global", but then didn't define any externs for that class. Does your project have such a class? Or are you trying to call something like self.addEventListener (also could be on window, top, etc)? If the latter, try Elemental2's DomGlobal.self.addEventListener(), which already is defined correctly.

[niloc132]

Note that this is the same error, self isn't defined. There might be some other global reference you can use in its place, but I don't write enough server-side JS to know what it would be at this time. Poking quickly at a node console, I see this is defined, and has fetch() defined on it, and goog.global (aka Js.global()) would access it to..

I do see global defined though, and it is a reference to this, so global.fetch() should work. That is, make a public static field like this:

@JsType(isNative = true, name = "global", namespace = JsPackage.GLOBAL)
public class NodeGlobal {
  public static Window global;
}

That would technically let you reference js global.global (which exists), and then use other functions on window.

With that said.... DomGlobal.fetch() is a function, and it is declared as actually on the global namespace (via goog.global), so I think that will work as-is - you don't need DomGlobal.self.fetch().

[faveoled]

Still haven't got any luck (will try again sometimes in the future)

DomGlobal.fetch("https://google.com")

TypeError: ha.fetch is not a function
    at /home/user/Dev/Java/j2cl-node/target/app-1.0-SNAPSHOT/app/app.js:16:16
    at Object.<anonymous> (/home/user/Dev/Java/j2cl-node/target/app-1.0-SNAPSHOT/app/app.js:17:159)
    at Object.<anonymous> (/home/user/Dev/Java/j2cl-node/target/app-1.0-SNAPSHOT/app/app.js:17:171)
    at Module._compile (node:internal/modules/cjs/loader:1159:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1213:10)
    at Module.load (node:internal/modules/cjs/loader:1037:32)
    at Module._load (node:internal/modules/cjs/loader:878:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
    at node:internal/main/run_main_module:23:47

NodeGlobal.global.fetch("https://google.com")

TypeError: Cannot read properties of undefined (reading 'fetch')
    at /home/user/Dev/Java/j2cl-node/target/app-1.0-SNAPSHOT/app/app.js:16:23
    at Object.<anonymous> (/home/user/Dev/Java/j2cl-node/target/app-1.0-SNAPSHOT/app/app.js:17:182)
    at Object.<anonymous> (/home/user/Dev/Java/j2cl-node/target/app-1.0-SNAPSHOT/app/app.js:17:194)
    at Module._compile (node:internal/modules/cjs/loader:1159:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1213:10)
    at Module.load (node:internal/modules/cjs/loader:1037:32)
    at Module._load (node:internal/modules/cjs/loader:878:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
    at node:internal/main/run_main_module:23:47

[niloc132]

Did the externs solve your global addEventListener problem at least? I didnt see you respond to that part, or to the question about warnings in the build.

[faveoled]

Externs help with a compilation failure, but I haven't succeeded with global JS calls. In the case of empty JS output no warnings were there

[niloc132]

Okay - sounds like we could do with a test case to confirm if our repo or forks introduced something, if there is an upstream bug, or something subtle wrong with your code.