func alertDialog(title, text, level string) (ret bool, err error) {
	defer func() {
		e := recover()
		if e == nil {
			return
		}
		if e, ok := e.(*js.Error); ok {
			err = e
		} else {
			panic(e)
		}
	}()
	ret = true
	js.Global.Call("alert", level+" "+title+"\n\n"+text)
	return
}
alert displays alert.
package dlgs
import (
	"github.com/gopherjs/gopherjs/js"
)
func Info(title, text string) (ret bool, err error) {
	return alertDialog(title, text, "\u24d8")
}
func Warning(title, text string) (ret bool, err error) {
	return alertDialog(title, text, "\u26a0")
}
func Error(title, text string) (ret bool, err error) {
	return alertDialog(title, text, "\u166e")
}
func Question(title, text string, defaultCancel bool) (ret bool, err error) {
	defer func() {
		e := recover()
		if e == nil {
			return
		}
		if e, ok := e.(*js.Error); ok {
			err = e
		} else {
			panic(e)
		}
	}()
	ret = js.Global.Call("confirm", "\u2753 "+title+"\n\n"+text).Bool()
	return
}