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Simplify the basic Wasm example, provide a simpler index.html that runs Wasm on start.

Dmitri Shuralyov 2018-09-10 02:12:20 -04:00
parent 2729aa49b0
commit 8e6e9199eb
1 changed files with 33 additions and 36 deletions
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69
WebAssembly.md

@ -17,65 +17,62 @@ compile: unknown architecture "wasm"
# Example # Example
To compile the basic Go program for the web: To compile a basic Go package for the web:
```go ```go
package main package main
import "fmt"
func main() { func main() {
println("Hello, WebAssembly!") fmt.Println("Hello, WebAssembly!")
} }
``` ```
Run: Run:
```sh ```sh
$ GOOS=js GOARCH=wasm go build -o test.wasm main.go $ GOOS=js GOARCH=wasm go build -o main.wasm
``` ```
And copy over the HTML & JS support files: Create an `index.html` file:
```HTML
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<script src="wasm_exec.js"></script>
<script>
const go = new Go();
WebAssembly.instantiateStreaming(fetch("main.wasm"), go.importObject).then((result) => {
go.run(result.instance);
});
</script>
</head>
<body></body>
</html>
```
And copy over the JavaScript support file:
```sh ```sh
$ cp $(go env GOROOT)/misc/wasm/wasm_exec.{html,js} . $ cp $(go env GOROOT)/misc/wasm/wasm_exec.js .
``` ```
Then serve those three files (`wasm_exec.html`, `wasm_exec.js`, and `test.wasm`) to a web browser. Then serve those three files (`index.html`, `wasm_exec.js`, and `main.wasm`) to a web browser. For example, with [`goexec`](https://github.com/shurcooL/goexec#goexec):
For a basic HTTP server: ```sh
$ goexec 'http.ListenAndServe(":8080", http.FileServer(http.Dir(".")))'
```go
package main
import (
"flag"
"log"
"net/http"
"strings"
)
var (
listen = flag.String("listen", ":8080", "listen address")
dir = flag.String("dir", ".", "directory to serve")
)
func main() {
flag.Parse()
log.Printf("listening on %q...", *listen)
log.Fatal(http.ListenAndServe(*listen, http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
if strings.HasSuffix(req.URL.Path, ".wasm") {
resp.Header().Set("content-type", "application/wasm")
}
http.FileServer(http.Dir(*dir)).ServeHTTP(resp, req)
})))
}
``` ```
Now navigate to http://localhost:8080/wasm_exec.html, click "Run", and you should see the output in the JavaScript debug console. (Or use your own [basic HTTP server command](https://play.golang.org/p/pZ1f5pICVbV).)
Finally, navigate to http://localhost:8080/index.html, open the JavaScript debug console, and you should see the output. You can modify the program, rebuild `main.wasm`, and refresh to see new output.
# Interacting with the DOM # Interacting with the DOM
See https://tip.golang.org/pkg/syscall/js/ See https://godoc.org/syscall/js.
# Debugging # Debugging