command-handling

command-handling

Table of contents

• Introduction
• Installation
• How to use
  • Command line structure
  • Methods
  • Data structures
  • Usage
• Examples
• Thank you!

1. Introduction

This is a lightweight library that is using for Node.js CLI applications. This library is also using for the project code-template-generator.

You should be using command-handling for a small CLI application that has not many complex features. You can view Commander.js if you are thinking about a great Node.js CLI application.

command-handling help you analyse a command line that entered by an end-user. It analyses the command line and catches the arguments that you may be waiting for then you decide what you want to do with the raw data after parsing.

2. Installation

$ npm install --save command-handling

3. How to use

Command line structure

The simple command line structure is used in this library:

$ command [-option][--alias] [--sub-option] [argument]

• An option has only an alias (main flag).
• An option has many sub options and they depend on the main flag is above.
• Use cases:
  • command (only command without anything)
  • command [argument]
  • command [-option][--alias]
  • command [-option][--alias] [argument]
  • command [-option][--alias] [--sub-option]
  • command [-option][--alias] [--sub-option] [argument]
  • command [--sub-option] [argument]

Tips! View the examples for code-template-generator to know more about how this library is used in another project.

Methods

Method	Argument	Description
.option()	<flag>, [alias], [description]	Option definition
.subOption()	<mainFlag>, <subFlag>, description	Sub option definition
.showOptions()	-	It returns an option list in an object array
.parse()	<process.argv>	Parse the command line

You can use method chaining for these methods:

• option
• subOption
• parse <- This method must be in the end of chaining.

Tip! View the examples for more details.

Data structures

1. A object is returned when the method .parse(process.argv) is called. The object is needed for the application development.

{   // The default result structure
    mainFlag: null,
    subFlags: [],
    argument: null,
    commandLength: 0,
    unknowns: []
}

• It depends on the mainFlag that may be found in the first position of the command line or not.
  • mainFlag is found -> subFlag is an array of all sub flags that are found in the input command line and they are filtered by the mainFlag.
  • mainFlag isn't found -> subFlag is an array of all sub flags that are found in the input command line and defined for the application.
• argument is in the last position of the input command line.
• unknowns is all things that command-handling can not analyze for a input command line.

View more the examples here.

2. An object array is returned when the method .showOptions() is called. It's helpful for a help function in a CLI application.

[   // All options
    {   // Option 1
        flag: '',     // It's mean the main flag
        alias: '',
        description: '',
        subFlags: [
            {
                flag: '', // Sub flag 1
                description: ''
            },
            {
                flag: '', // Sub flag n
                description: ''
            }
        ]
    },
    {   // Option n
        ...
    }
]

Tip! View the examples for more detail.

Usage

• Step 1: Import the Command object from command-handling library.
  • const { Command } = require('command-handling');
• Step 2: Declare an object for your app. You decide its name.
  • const command = new Command();
• Step 3: You can use method chaining for the command object. You define all options and sub options in this step:
  • Option: .option(<flag>, [alias], [description])
  • Sub option: .subOption(<mainFlag>, <subFlag>, [description])
• Step 4: Parse the command line and remember at this step is in the end of chaining. There are few ways to parse the command line:
  • .parse(process.argv); -> End of method chaining.
  • const result = command.parse(process.argv); -> Declare a separate variable to get back the result object that is needed for the application development.
• Extra: Using the method .showOptions() to get back an option list are defined above for the help function.
  • Example: const optionList = command.showOptions();

4. Examples

Example 1

const { Command } = require('command-handling');
const command = new Command();

command
    .option("-v", "--version", "View the installed version")
    .option("-help", "--help", "View the help information")
    .option("-cf", "--config", "Config for this app")
    .subOption("-cf", "--set-asset", "Store the asset directory path")
    .subOption("-cf", "--view-asset", "View the asset directory path")
    .parse(process.argv); // Parsing is in the end of chaining

const optionList = command.showOptions();

console.log(optionList); // It returns an array with all defined options

Example 2

const { Command } = require('command-handling');
const command = new Command();

command
    .option("-v", "--version", "View the installed version")
    .option("-h", "--help", "View help documentation")
    .option("-cf", "--config", "Config for this app")
    .subOption("-cf", "--set-asset", "Store the asset directory path")
    .subOption("-cf", "--view-asset", "View the asset directory path");

/* Parsing result is stored in a separate variable
const parsedCommand = command.parse(process.argv);
console.log(parsedCommand); */

// Another way for the command line parsing
const { mainFlag } = command.parse(process.argv);

switch (mainFlag) {
    case "-v":
        console.log("Version 1.0.0");
        break;

    case "-h":
        const optionList = command.showOptions();
        showHelpInformation(optionList);

        break;

    default:
        break;
}

function showHelpInformation(optionList){
    console.log("Welcome to help documentation");
    console.log(optionList); // Using for testing
}

View more the examples here.

5. Thank you!

Many thanks to Commander.js for the inspiration.