Vecty: AddScript function manual test.

main.go

package main

import (
	"errors"
	"sync"
	"syscall/js"
	"time"

	"github.com/hexops/vecty"
	"github.com/hexops/vecty/elem"
)

func main() {
	vecty.SetTitle("Hello Vecty!")
	vecty.RenderBody(&PageView{})
}

// PageView is our main page component.
type PageView struct {
	vecty.Core
}

// Render implements the vecty.Component interface.
func (p *PageView) Render() vecty.ComponentOrHTML {
	if AddScript(
		"https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.min.js",
		time.Millisecond*30000,
		make(map[string]interface{}),
	) == nil {
		println("bootstrap works like a dream")
	}

	if err := AddScript(
		"http://localhost:8000/slow.js",
		time.Millisecond*3,
		make(map[string]interface{}),
	); err != nil {
		println("error throwing like a dream")
		println(err.Error())
		if errors.Is(err, ErrTimeout) {
			println("yes box")
		}
	}

	return elem.Body(
		vecty.Text("Hello Vecty!"),
	)
}

var ErrTimeout = errors.New("timeout while obtaining script from URL")
var ErrTimeoutGreaterThan = errors.New("timeout value has to be greater than zero")

func AddScript(url string, timeout time.Duration, attributes map[string]interface{}) error {
	if timeout <= 0 {
		return ErrTimeoutGreaterThan
	}
	script := js.Global().Get("document").Call("createElement", "script")
	script.Set("src", url)
	for k, v := range attributes {
		script.Set(k, v)
	}

	quitCh := make(chan struct{})

	var f js.Func
	f = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
		defer f.Release()
		close(quitCh)
		script.Delete("onload")
		return nil
	})
	script.Set("onload", f)
	js.Global().Get("document").Get("head").Call("appendChild", script)

	var err error
	var wg sync.WaitGroup
	wg.Add(1)
	go func(t time.Duration) {

		tic := time.NewTicker(10 * time.Millisecond)
		start := time.Now()
	loop:
		for {
			select {
			case <-quitCh:
				wg.Done()
				break loop
			case <-tic.C:
				if time.Since(start) > t {
					err = ErrTimeout
					wg.Done()
					break loop
				}
			}
		}
	}(timeout)
	wg.Wait()

	return err
}

slow.go

package main

import (
	"log"
	"net/http"
	"time"
)

func main() {
	http.HandleFunc("/slow.js", func(w http.ResponseWriter, r *http.Request) {
		time.Sleep(time.Second * 2)
		http.ServeFile(w, r, "test.js")
	})
	log.Println("listening to connections: 8000")
	log.Fatal(http.ListenAndServe(":8000", nil))
}