[Golang] GopherJS serve and build Command Usage

GopherJS provide command line tools but there is no enough documentation of the command. I gave the serve and build command a try and give a summary of the usage.

First we see the help of gopherjs command line tool:

$ gopherjs help
GopherJS is a tool for compiling Go source code to JavaScript.

Usage:
  gopherjs [command]

Available Commands:
  build       compile packages and dependencies
  get         download and install packages and dependencies
  install     compile and install packages and dependencies
  run         compile and run Go program
  test        test packages
  tool        run specified go tool
  serve       compile on-the-fly and serve

Flags:
      --color         colored output (default true)
  -m, --minify        minify generated code
  -q, --quiet         suppress non-fatal warnings
      --tags string   a list of build tags to consider satisfied during the build
  -v, --verbose       print the names of packages as they are compiled
  -w, --watch         watch for changes to the source files

Use "gopherjs [command] --help" for more information about a command.

Build Command Usage

We will try build command first. See the help of build command first:

$ gopherjs build --help
compile packages and dependencies

Usage:
  gopherjs build [packages] [flags]

Flags:
      --color           colored output (default true)
  -m, --minify          minify generated code
  -o, --output string   output file
  -q, --quiet           suppress non-fatal warnings
      --tags string     a list of build tags to consider satisfied during the build
  -v, --verbose         print the names of packages as they are compiled
  -w, --watch           watch for changes to the source files

Now I have a Go program named dom.js, put under . directory. Compile this file to JavaScript by:

$ gopherjs build dom.go -o dom.js

The JavaScript output file will be dom.js, put under . directory.

Next we try the -w flag of build command:

$ gopherjs build dom.go -w -o dom.js

The GopherJS command line tool will watch the directory, and if you make any changes of dom.go, it will automatically recompile the Go code to JavaScript. This feature is great for daily development.

Assume GOPATH is set, and you put the dom.go under $(GOPATH)/src/demo directory, you can tell GopherJS command line tool to look for the demo directory by:

$ gopherjs build demo -w -o src/demo/dom.js

The command line tool will compile the dom.go under $(GOPATH)/src/demo and the JavaScript output file will be $(GOPATH)/src/demo/dom.js.

Serve Command Usage

See the help of serve command first:

$ gopherjs serve --help
compile on-the-fly and serve

Usage:
  gopherjs serve [flags]

Flags:
      --color         colored output (default true)
      --http string   HTTP bind address to serve (default ":8080")
  -m, --minify        minify generated code
  -q, --quiet         suppress non-fatal warnings
      --tags string   a list of build tags to consider satisfied during the build
  -v, --verbose       print the names of packages as they are compiled

Global Flags:
  -w, --watch   watch for changes to the source files

Run the command without any flag:

$ gopherjs serve

The GopherJS command line tool will serve $(GOPATH)/src directory by default. It looks like there is no way to change the serving directory. Open your browser at http://localhost:8080 to visit the webpage.

I like to visit the webpage at http://localhost:8000. Change the port by:

$ gopherjs serve --http ":8000"

I try to run the serve command with -w flag but it looks like the command line tool did not watch the changes and recompile for me. So I guess the -w flag is useless combined with serve command.

Tested on: Ubuntu Linux 15.10, Go 1.5.2.

References:

[1]	GopherJS - A compiler from Go to JavaScript (GitHub, GopherJS Playground, )

[2]	Getting Started with GopherJS

[3]	GopherJSの紹介 - GolangRdyJp

[4]	albrow/gopherjs-live · GitHub (Automatic watching and recompiling for gopherjs)

[5]	ajhager/srvi · GitHub (Quickly build, serve, run, and refresh your GopherJS programs)

[6]	cmd/gopherjs_serve_html at master · shurcooL/cmd · GitHub

[7]	Add "gopherjs serve" command · Issue #121 · gopherjs/gopherjs · GitHub

[8]	It's easy to get an infinite loop with the watch flag · Issue #212 · gopherjs/gopherjs · GitHub