add help command-line argument

README.md

@@ -27,6 +27,12 @@ Contributions are welcome! Open a pull request to fix a bug, or open an issue to
   cat sample.json | node json-to-go.js
   ```
 
+- For more options, check the help page
+
+  ```sh
+  node json-to-go.js --help
+  ```
+
 ### Credits
 
 JSON-to-Go is brought to you by Matt Holt ([mholt6](https://twitter.com/mholt6)).

json-to-go-v2.js

@@ -509,6 +509,25 @@ if (typeof module === 'undefined' || !module.parent) {
 		process.stdout.write(output.go)
 	}
 
+	function printHelp() {
+		const path = require('path');
+		const scriptname = path.basename(process.argv[1])
+
+		console.log(`\
+Usage: node ${scriptname} [OPTION]... [FILE]
+Convert json to go file and prints the result on stdout.
+
+Optional arguments:
+	--help               Print this help page
+	--all-omitempty      Make all fields "omitempty" (Default: false)
+	--examples           Add examples to go struct. Currently only works without flatten. (Default: false)
+	--flatten            Flatten go struct (Default: true)
+	--typename=NAME      Use a specific name for typename (Default: "AutoGenerated")
+
+All arguments can be inverted by specifing "--no-...", for example "--no-examples".
+		`)
+	}
+
 	process.argv.forEach((val, index) => {
 		if (index < 2)
 			return
@@ -544,8 +563,12 @@ if (typeof module === 'undefined' || !module.parent) {
 			case "all-omitempty":
 				options.allOmitempty = argument.value
 				break
+			case "help":
+				printHelp()
+				process.exit(0)
 			default:
 				console.error(`Unexpected argument ${val} received`)
+				printHelp()
 				process.exit(1)
 		}
 	})