Add cli usage information (#423)

* add cli usage: `next init`

* add cli usage: `next --help`

* add cli usage: `next build --help`

* add cli usage: `next dev --help`

* add cli usage: `next init --help`

* add cli usage: `next start --help`

* use set

* build, start and dev all accept a directory

* typo and conciseness

bin/next

@@ -6,15 +6,29 @@ import { watchFile } from 'fs'
 
 const defaultCommand = 'dev'
 const commands = new Set([
-  defaultCommand,
   'init',
   'build',
-  'start'
+  'start',
+  defaultCommand
 ])
 
 let cmd = process.argv[2]
 let args
 
+if (new Set(['--help', '-h']).has(cmd)) {
+  console.log(`
+    Usage
+      $ next <command>
+
+    Available commands
+      ${Array.from(commands).join(', ')}
+
+    For more information run a command with the --help flag
+      $ next init --help
+  `)
+  process.exit(0)
+}
+
 if (commands.has(cmd)) {
   args = process.argv.slice(3)
 } else {

bin/next-build

@@ -11,6 +11,20 @@ const argv = parseArgs(process.argv.slice(2), {
   boolean: ['h']
 })
 
+if (argv.help) {
+  console.log(`
+    Description
+      Compiles the application for production deployment
+
+    Usage
+      $ next build <dir>
+
+    <dir> represents where the compiled .next folder should go.
+    If no directory is provided, .next will be created in the current directory
+  `)
+  process.exit(0)
+}
+
 const dir = resolve(argv._[0] || '.')
 
 build(dir)

bin/next-dev

@@ -16,6 +16,25 @@ const argv = parseArgs(process.argv.slice(2), {
   }
 })
 
+if (argv.help) {
+  console.log(`
+    Description
+      Starts the application in development mode (hot-code reloading, error
+      reporting, etc)
+
+    Usage
+      $ next dev <dir> -p <port number>
+
+    <dir> represents where the compiled .next folder should go.
+    If no directory is provided, .next will be created in the current directory
+
+    Options
+      --port, -p      A port number on which to start the application
+      --help, -p      Displays this message
+  `)
+  process.exit(0)
+}
+
 const dir = resolve(argv._[0] || '.')
 
 const srv = new Server({ dir, dev: true })

bin/next-init

@@ -11,6 +11,23 @@ const argv = parseArgs(process.argv.slice(2), {
   boolean: ['h']
 })
 
+if (argv.help) {
+  console.log(`
+    Description
+      Scaffolds a simple project structure to get started quickly
+
+    Usage
+      $ next init <dir>
+
+      If no directory is provided the current directory will be used.
+
+    Options
+      --help, -p      Displays this message
+  `)
+
+  process.exit(0)
+}
+
 const dir = resolve(argv._[0] || '.')
 
 if (basename(dir) === 'pages') {

bin/next-start

@@ -15,6 +15,26 @@ const argv = parseArgs(process.argv.slice(2), {
   }
 })
 
+if (argv.help) {
+  console.log(`
+    Description
+      Starts the application in production mode.
+      The application should be compiled with \`next build\` first.
+
+    Usage
+      $ next start <dir> -p <port>
+
+    <dir> is the directory that contains the compiled .next folder
+    created by running \`next build\`.
+    If no directory is provided, the current directory will be assumed.
+
+    Options
+      --port, -p      A port number on which to start the application
+      --help, -p      Displays this message
+  `)
+  process.exit(0)
+}
+
 const dir = resolve(argv._[0] || '.')
 
 const srv = new Server({ dir })