How to generate a wasm file using golang and execute it on a browser
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What is webassembly?
Webassembly is a binary format that can be supported in web browsers or V8 environments. For more information, you can check this answer.
Start
Need to upgrade go to version 1.11 first
Write go files that need to be compiled into wasm files
/ / main.go
Package main
Func main () {
Println ("Hello, WebAssembly!")
}
Execute the build command
GOARCH=wasm GOOS=js go build-o test.wasm main.go
Note that this command is executed under the mac or linux operating system. Under windows, the environment variable should be set and then the compile command should be executed.
$env:GOARCH= "wasm"; $env:GOOS= "js"
Go build-o test.wasm main.go
After the command is executed, the test.wasm file is generated, which is the binary file that can be run on the browser.
Add additional dependencies
Copy the wasm_exec.html and wasm_exec.js files under $(go env GOROOT) / misc/wasm/ to the current directory
Set up web server
/ / test.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)
})
}
Run the web service
Go run test.go
test
Open http://localhost:8080/wasm_exec.html in the browser and click the run button on the page to see the console printing Hello, WebAssembly!
So we can use go to write a program that can run in the browser.
How to use js
Using go's js library syscall/js
/ / main.go
Package main
Import "syscall/js"
Func sum (args [] js.Value) {
Var sum int
For _, val: = range args {
Sum + = val.Int ()
}
Println (sum)
}
Func registerCallbacks () {
Js.Global () .Set ("sum", js.NewCallback (sum))
}
Func main () {
C: = make (chan struct {}, 0)
Println ("Hello, WebAssembly!")
RegisterCallbacks ()
