Blog: https://withblue.ink/2020/10/03/go-webassembly-http-requests-and-promises.html

js-native-object-from-wasm.go

// Copyright (C) 2020 Alessandro Segala (ItalyPaleAle)
// License: MIT

// MyGoFunc returns a Go time.Time to JavaScript
func MyGoFunc() js.Func {
	return js.FuncOf(func(this js.Value, args []js.Value) interface{} {
		// Get the current time as a Go time.Time object
		now := time.Now()
		// Get the Date object constructor from JavaScript
		dateConstructor := js.Global().Get("Date")
		// Return a new JS "Date" object with the time from the Go "now" variable
		// We're passing the UNIX timestamp to the "Date" constructor
		// Because JS uses milliseconds for UNIX timestamp, we need to multiply the timestamp by 1000
		return dateConstructor.New(now.Unix() * 1000)
	})
}