How to await a Promise to resolve or reject? #694
Description
I was trying to provide some go function like http.Get to be used in js by using Promise, the problem is that the main loop exited immediately without waiting for the promise to fulfill.
A minimal snippet:
package main
import (
"log"
"net/http"
"github.com/dop251/goja"
"github.com/dop251/goja_nodejs/eventloop"
)
func get(args goja.FunctionCall, vm *goja.Runtime) goja.Value {
promise, resolve, reject := vm.NewPromise()
ev := vm.Get(`__ev`).Export().(*eventloop.EventLoop)
go func() {
log.Println(`before get`)
rsp, err := http.Get(`http://example.com`)
log.Println(`after get`)
if err != nil {
ev.RunOnLoop(func(vm *goja.Runtime) {
reject(vm.ToValue(err))
})
return
}
ev.RunOnLoop(func(vm *goja.Runtime) {
resolve(vm.ToValue(rsp))
})
}()
return vm.ToValue(promise)
}
func main() {
ev := eventloop.NewEventLoop()
ev.Run(func(vm *goja.Runtime) {
vm.Set(`__ev`, ev)
vm.Set(`get`, get)
})
ev.Run(func(vm *goja.Runtime) {
// cannot `await get` here, because await cannot be used outside
// an async function, hence syntax error.
// SyntaxError: SyntaxError: (anonymous): Line 1:7 Unexpected identifier
p, _ := vm.RunString(`get('http://example.com')`)
log.Println(p.Export().(*goja.Promise).State())
})
ev.Run(func(r *goja.Runtime) {
})
}The go main() exited before before get log can be printed.
How can I wait for the Promise to fulfill?