Fullstack Javascript
Course Notes
02 - Building CLI applications with Node.js
4. Rock, Paper, Scissors CLI Example

4. Rock, Paper, Scissors CLI Example

Objective

Create a Command-Line Interface (CLI) application in Node.js where users can play Rock, Paper, Scissors against the computer. The app will start with single-round gameplay and expand to include a “best of three” mode through a feature branch and pull request workflow.

Requirements

Functionality

  • Single-Round Gameplay:

    • Allow the user to choose rock, paper, or scissors via command-line arguments.
    • Generate a random choice for the computer.
    • Determine and display the winner of the round.
    • Handle invalid input gracefully with an informative error message.

  • Best of Three Mode:

    • Add a feature to play a “best of three” match.
    • Track and display the score for the user and computer over three rounds.
    • Display the winner of the match after three rounds.
    • Ensure proper error handling for invalid input within the loop.

Implementation Steps

Part 1: Single-Round Gameplay

  1. Set Up the Project:

    • Initialize a new git repository with git init.
    • Create a new Node.js project using npm init.
    • Create a new JavaScript file, rps.js.
    • Ensure it can be run with Node.js.

  2. Implement User Input:

    • Use process.argv to capture the user’s choice (rock, paper, or scissors).
    • Validate the input to ensure it is one of the three valid options.

  3. Generate a Random Choice for the Computer:

    • Create an array of choices: rock, paper, scissors.
    • Randomly select one for the computer.

  4. Determine the Winner:

    • Compare the user’s choice with the computer’s choice.
    • Implement the logic for deciding the outcome (win, lose, tie).

  5. Output the Results:

    • Print the user’s choice, the computer’s choice, and the result.

Part 2: Adding “Best of Three” Mode

  1. Branch Creation:

    • Create a new branch named best-of-three.

  2. Update Input Handling:

    • Add support for a new command: best-of-3.

  3. Loop for Three Rounds:

    • Implement a loop to play three rounds of Rock, Paper, Scissors.
    • Track the score for both the user and the computer.

  4. Score Tracking and Output:

    • Print the result of each round.
    • At the end, display the final scores and declare the winner of the match.

  5. Handle Errors:

    • Ensure proper error messages for invalid input within the loop.

Part 3: PR Workflow

  1. Push the Branch:

    • Push the best-of-three branch to the repository.

  2. Create a Pull Request:

    • Open a PR to merge best-of-three into the main branch.

  3. Review the Changes:

    • Walk through the changes with the students.
    • Discuss the purpose of the new feature and how it was implemented.

  4. Merge the PR:

    • Merge the branch and pull the changes into the local environment.

Part 4: Demonstration and Expansion

  1. Test the Final App:

    • Show how to use the single-round mode and “best of three” mode.

  2. Discuss Potential Improvements:

    • Ideas for future development (e.g., customizable match lengths, user names, advanced statistics).

Additional Requirements

  • Ensure the project has a package.json file.
  • Use git for version control and demonstrate proper branching and pull request workflows.