Problems with Go 1.11rc1 [SOLVED] #1
Comments
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If you're in the correct directory, try just |
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if there's no package argument, is uses |
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Cool! It works, thanks a lot! And is it genuinely building a server-side wasm file and serving that? |
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It's actually very simple - no magic going on at all... It does this:
It's a very simple system... The complexity will come in future when we get the package splitting working... that'll be tricky. |
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It makes life very easy, at least for simple examples. I was experimenting with deploying to Thanks again for this! |
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No problem! Next I'm going to do a |
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Just one question, if I may. Do you have, or do you know of any more complicated examples of Golang WASM code? I've tried googling but the ones I have found so far all fail to build, or If they do build, they don't run properly at |
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It would be great if you can show me any examples of projects that should work but don't in jsgo.io... It's always worth remembering that jsgo only serves the wasm file - if the project depends on assets being served (CSS etc) they will need to be served from somewhere else. I've usually used rawgit.com for this... I haven't actually done much WASM examples, but I did a lot of GopherJS things and they should be pretty trivial to convert... I'll have a go later today. |
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I’ll see what I can do.
…On 16 Aug 2018, 10:09 +0100, Dave Brophy ***@***.***>, wrote:
It would be great if you can show me any examples of projects that should work but don't in jsgo.io... It's always worth remembering that jsgo only serves the wasm file - if the project depends on assets being served (CSS etc) they will need to be served from somewhere else. I've usually used rawgit.com for this...
I haven't actually done much WASM examples, but I did a lot of GopherJS things and they should be pretty trivial to convert... I'll have a go later today.
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Okay, here is an example of some code that builds but which doesn't appear to run properly when deployed... package main // import "lazyhackergo.com/wasmgo"
import (
"math"
"strconv"
"syscall/js"
"time"
"lazyhackergo.com/browser"
)
var signal = make(chan int)
// Example of a callback function that can be registered.
func cb(args []js.Value) {
println("callback")
}
// cbQuit is a function that gets attached to browser event.
func cbQuit(e js.Value) {
println("got Quit event callback!")
window := browser.GetWindow()
window.Document.GetElementById("runButton").SetProperty("disabled", false)
window.Document.GetElementById("quit").SetAttribute("disabled", true)
signal <- 0
}
// keepalive waits for a specific value as a signal to quit. Browsers still run
// javascript and wasm in a single thread so until the wasm module releases
// control, the entire browser window is blocked waiting for the module to
// finish. It looks like that while waiting for the blocked channel, the
// browser window gets control back and can continue its event loop.
func keepalive() {
for {
m := <-signal
if m == 0 {
println("quit signal received")
break
}
}
// select {} also seems to work but the following doesn't:
// select {
// case m <-signal:
// // do something
// default:
// // wait
// }
}
func main() {
q := js.NewEventCallback(js.StopImmediatePropagation, cbQuit)
// defer q.Close()
c := js.NewCallback(cb)
// defer c.Close()
browser.Invoke(c) //js.ValueOf(c).Invoke()
window := browser.GetWindow()
// Disable the Run button so the module doesn't get executed again while it
// is running. If it runs while a previous instance is still running then
// the browswer will give an error.
window.Document.GetElementById("runButton").SetAttribute("disabled", true)
// Attach a browser event to the quit button so it calls our Go code when
// it is clicked. Also enable the Quit button now that the module is running.
window.Document.GetElementById("quit").AddEventListener(browser.EventClick, q)
window.Document.GetElementById("quit").SetProperty("disabled", false)
//js.Global.Get("document").Call("getElementById", "quit").Call("addEventListener", "click", js.ValueOf(q))
window.Alert("Triggered from Go WASM module")
window.Console.Info("hello, browser console")
canvas, err := window.Document.GetElementById("testcanvas").ToCanvas()
if err != nil {
window.Console.Warn(err.Error())
}
// Draw a cicule in the canvas.
canvas.Clear()
canvas.BeginPath()
canvas.Arc(100, 75, 50, 0, 2*math.Pi, false)
canvas.Stroke()
// A Go routine that prints its counter to the canvas.
canvas.Font("30px Arial")
time.Sleep(5 * time.Second)
go func() {
for i := 0; i < 10; i++ {
canvas.Clear()
canvas.FillText(strconv.Itoa(i), 10, 50)
time.Sleep(1 * time.Second) // sleep allows the browser to take control otherwise the whole UI gets frozen.
}
canvas.Clear()
canvas.FillText("Stop counting!", 10, 50)
}()
window.Console.Info("Go routine running while this message is printed to the console.")
keepalive()
} |
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Just to show that not everything is bad in example-land, this one works... package main
import(
"syscall/js"
"github.com/PaulRosset/go-hacknews"
)
func topStories() []hacknews.Post {
// This is an example from:
// https://github.com/PaulRosset/go-hacknews
// Copyright (c) 2017 Paul Rosset
// See LICENSE in the link above.
init := hacknews.Initializer{Story: "topstories", NbPosts: 10}
codes, err := init.GetCodesStory()
if err != nil {
panic(err)
}
posts, err := init.GetPostStory(codes)
if err != nil {
panic(err)
}
return posts
}
var document = js.Global().Get("document")
func renderPost(post hacknews.Post, parent js.Value) {
// Creates the following HTML elements
// <li>
// <a href="{URL}">{Title}</a>
// </li>
li := document.Call("createElement", "li")
a := document.Call("createElement", "a")
text := document.Call("createTextNode", post.Title)
a.Set("href", post.Url)
a.Call("appendChild", text)
li.Call("appendChild", a)
parent.Call("appendChild", li)
}
func renderPosts(posts []hacknews.Post, parent js.Value) {
ul := document.Call("createElement", "ul")
parent.Call("appendChild", ul)
for _, post := range(posts) {
renderPost(post, ul)
}
}
func main() {
posts := topStories()
body := document.Get("body")
renderPosts(posts, body)
} |
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The first example is looking for a DOM element called "runButton"... I believe in the example index page in the Go repo it has a run button instead of running the code when the page loads... This will need some tweaks... |
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This one doesn't build at all... package main
import (
"syscall/js"
"github.com/shurcooL/github_flavored_markdown"
)
var document = js.Global().Get("document")
func getElementByID(id string) js.Value {
return document.Call("getElementById", id)
}
func renderEditor(parent js.Value) js.Value {
editorMarkup := `
<div id="editor" style="display: flex; flex-flow: row wrap;">
<textarea id="markdown" style="width: 50%; height: 400px"></textarea>
<div id="preview" style="width: 50%;"></div>
<button id="render">Render Markdown</button>
</div>
`
parent.Call("insertAdjacentHTML", "beforeend", editorMarkup)
return getElementByID("editor")
}
func main() {
quit := make(chan struct{}, 0)
// See example 2: Enable the stop button
stopButton := getElementByID("stop")
stopButton.Set("disabled", false)
stopButton.Set("onclick", js.NewCallback(func([]js.Value) {
println("stopping")
stopButton.Set("disabled", true)
quit <- struct{}{}
}))
// Simple markdown editor
editor := renderEditor(document.Get("body"))
markdown := getElementByID("markdown")
preview := getElementByID("preview")
renderButton := getElementByID("render")
renderButton.Set("onclick", js.NewCallback(func([]js.Value) {
// Process markdown input and show the result
md := markdown.Get("value").String()
html := github_flavored_markdown.Markdown([]byte(md))
preview.Set("innerHTML", string(html))
}))
<-quit
editor.Call("remove")
} |
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You may be interested to know that I've been building these with Go Modules activated (GO111MODULE=on) and after running |
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OK so I just deployed a new version... Do a <!doctype html>
<!--
Copyright 2018 The Go Authors. All rights reserved.
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file.
-->
<html>
<head>
<meta charset="utf-8">
<title>Go wasm</title>
</head>
<body>
<script src="{{ .Script }}"></script>
<script>
if (!WebAssembly.instantiateStreaming) { // polyfill
WebAssembly.instantiateStreaming = async (resp, importObject) => {
const source = await (await resp).arrayBuffer();
return await WebAssembly.instantiate(source, importObject);
};
}
const go = new Go();
let mod, inst;
WebAssembly.instantiateStreaming(fetch("{{ .Binary }}"), go.importObject).then((result) => {
mod = result.module;
inst = result.instance;
document.getElementById("runButton").disabled = false;
});
async function run() {
console.clear();
await go.run(inst);
inst = await WebAssembly.instantiate(mod, go.importObject); // reset instance
}
</script>
<button onClick="run();" id="runButton" disabled>Run</button>
</body>
</html> |
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The markdown example built fine and deployed for me but doesn't run... ... it doesn't look like a |
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Good work Dave! I can confirm that the example with the run button and the additional html file now works perfectly, if unspectacularly! |
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I don't know how familiar you are with Go Modules, but I've had some issues updating the package. Details are at golang/go#27028. Hopefully, Russ Cox will see the issue and answer it. We'll see! |
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I’m afraid I haven’t looked into modules yet. Is there something I need to add as a package author? I assume not until I want to enforce dependencies... |
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No worries Dave! I'll see if Russ Cox answers my question and I'll keep you posted - it's an area that every Golang package author will need to address sooner or later. |
Golang 1.11rc1
macOS 10.13.6
Hi Dave, I've run
go get -u github.com/dave/wasmgoon Go 1.11rc1 and as a result of Modules it had downloaded it togo/pkg/mod/github.com/dave/[email protected].I switched into the
helloworldfolder where there is amain.go.To save me having to type the full path, since I was there already, I tweaked the instructions to
wasmgo deploy helloworld. Not surprisingly, since there is no source file calledhelloworld, this didn't work.What do I have to do to get this to work?
Cheers,
Carl
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