Is it possible to explicitly call an exported Go WebAssembly function from JS?

Question

Is it possible to call a Go WebAssembly function, other than main, in Javascript?

Let me first show what I did. My Go functions are defined

Answer 1

Yes, it is possible. You can "export" a function to the global context (i.e. window in browser, global in nodejs):

js.Global().Set("add", js.FuncOf(addFunction))

Where "add" is the name that you can use to call the function from Javascript (window.add) and "addFunction" is a Go function in your Go code, next to your main.

Note that "addFunction" must follow that method signature:

package main

import (
    "syscall/js"
)

func addFunction(this js.Value, p []js.Value) interface{} {
    sum := p[0].Int() + p[1].Int()
    return js.ValueOf(sum)
}

func main() {
    c := make(chan struct{}, 0)

    js.Global().Set("add", js.FuncOf(addFunction))

    <-c
}

After "go.run(result.instance);" you can run.

go.run(result.instance);
add(100,200);