crt-terminal

CRT terminal

Simple retro styled React-hooks-based terminal shell.

Demo page.

Features

1. Smooth printing
2. Command history
3. Loader
4. Ability lock command input
5. Typescript and React
6. Hooks-based with event queues under the hood
7. Zero additional dependencies

Installation and basic usage

The best way to use crt-terminal is to install it from npm and include it into your app.

yarn add crt-terminal

npm install crt-terminal

Then you need to import Terminal, useEventQueue (or implement your own EventQueue) and line/words helpers (or corresponding enum with IDs).

Important! For better experience Terminal should be wrapped into a fixed size container.

import React from 'react';
import { Terminal, useEventQueue, textLine, textWord } from 'crt-terminal';

const bannerText = `
Hello world!

And not only world
`;

export default function App() {
  const eventQueue = useEventQueue();
  const { print } = eventQueue.handlers;

  return (
    <div style={{ width: '1000px', height: '600px' }}>
      <Terminal
        queue={eventQueue}
        banner={[textLine({ words: [textWord({ characters: bannerText })] })]}
        onCommand={(command) =>
          print([
            textLine({
              words: [
                textWord({ characters: 'You entered command: ' }),
                commandWord({ characters: command, prompt: '>' }),
              ],
            }),
          ])
        }
      />
    </div>
  );
}

Advanced usage and API reference

Required Props

1. queue: QueueInterface - state and api of useEventQueue
2. (command: string) => void - function to be called every time new command is submitted

Optional props

1. prompt?: string - prompt symbol before command input

2. cursorSymbol?: string - function to be called every time new command is submitted

3. maxHistoryCommands?: number - max number of commands to be memorized in commands history

4. banner?: PrintableItem - message to be printed after Terminal is mounted

5. loader?: Partial<LoaderConfig> - loader config, consist of:

   • slides: string[] - array of consecutive loader states
   • loaderSpeed: number - interval between state changes

6. printer?: Partial<PrinterConfig> - printer config, consist of:

   • printerSpeed: number - interval between state changes
   • charactersPerTick: number - characters to print on each tick

7. effects? enabling or disabling following effects:

   • scanner?: boolean - scanner line
   • pixels?: boolean - "pixels" effect
   • screenEffects?: boolean - screen shaking
   • textEffects?: boolean - text glow pulsing

Event Queue

The main part of public interface through which component communicates with outer world. useEventQueue exports event creators in handlers field of return object, namely:

1. print: (payload: PrintableItem) => void - prints a message on terminal "screen". Important! Print is async operation, so your next message will be printed as soon as the previous one is finished
2. clear: () => void - clears terminal "screen" with respect to printing queue
3. focus: () => void - focuses terminal input
4. lock: (payload: boolean) => void - locks/unlocks terminal input preventing any user attempt to enter a command
5. loading: (payload: boolean) => void - starts/ends loader. Important! Loading start locks input automatically, if it is not locked yet. Loading end unlocks input automatically, if it was locked by loader

You can use these handlers everywhere to fully control behavior of tour terminal.

If you don't like event creators, you can use enqueue from api field of return object. In this case you also need to import enums PrinterEvents and TerminalEvents. Important! To avoid possible bugs, you should pass newly created object into enqueue method

Sentence, Sentence Helpers

As one can notice print handler prints a PrintableItem. PrintableItem or sentence is an array of Lines. Line is essentially a new div on the screen, each line has field words with array of Words. There are two types of lines:

1. TextLine (larger x-padding, no y-padding)
2. CommandLine (smaller x-padding, y-padding).

Important! Each Lines and Words have common optional fields:

1. dataAttribute - data-crt-terminal attribute
2. className
3. id

Word is essentially a new span inside line. Word can be multilined, but aware of span intereactions whe one of them is multilined. Each word has characters filed with content of a word. There are quite few types of words:

1. AnchorWord - <a> element with optional href and onClick fields
2. TextWord - <span> element
3. ButtonWord - <button> element with optional onClick field
4. CommandWord - <span> element with required prompt field

There are two ways of creating Lines and Words:

1. Using helper functions textWord, buttonWord, commandWord, anchorWord, commandLine, textLine
2. Using object literals, in this cases you need to import WordTypes, LineTypes enums

Styling

Every element inside terminal has special fixed style you can safely refer to. You can also add your own className for lines and words.

Command history

Command history saves entered commands, but no more then maxHistoryCommands. You can get previous/next saved command by pressing Arrow Up / Arrow Down

License

MIT Licensed. Copyright (c) Dmitriy Lipin 2022.