Makitso Prompt

The terminal prompt used by Makitso.

yeh, yeh.. I started with Commander, it calls process.exit() for various reasons which made it difficult to use in a REPL. I then converted Makitso use Inquirer, but it doesn't like promises so much and I needed moar async. Enquirer was better in this respect, but then I got to implementing autocomplete and things got tricky again. I had varying success overriding parts of these modules, but it was harder to bend to them my will than I liked. The inbuilt Node readline module was much the same, so I started from scratch, pulling in some of the complex bits from readline and filling in the gaps.

The essential part of a commandline prompt is being able to act on key presses and modify the output in the terminal accordingly. I've attempted to make this as simple as possible with makitso-prompt by allowing pure functions to be used as key-press processors which modify a state object which is then rendered to the terminal. Much of the logic is also broken into easily replaceable functions for customisation.

Usage

Simple

This will simply echo entered commands

const { Prompt } = require("makitso-prompt");
const prompt = new Prompt();
const command = prompt.start().then(console.log);

Custom prompt

const prompt = new Prompt({ prompt: chalk`{blue aPrompt> }` });
const command = prompt.start().then(console.log);

Include a header above the prompt and a footer below it

const prompt = new Prompt();
const header = "A line above the prompt";
const footer = "A line below the prompt\nAnother line";
const command = prompt.start({ header, footer }).then(console.log);

Add a custom keypress handler

const { keyPressHistory } = require("makitso-prompt");
const prompt = new Prompt();
Object.assign(prompt, { keyPressers: [...prompt.keyPressers, keyPressHistory] });
const command = prompt.start().then(console.log);

Keypress handlers

A keypress handler is an object with a keyPress method.

Keypress handlers keyPress methods are called each time a key is pressed.

Keypress handlers are called in the order of the keypressers array.

The keyPress method is called with the app state object and a press object.

Keypress handlers use the press and/or state objects to decide what, if anything, needs to be changed in the state object. Changes are made using state methods or using the applyPatch function from makitso-prompt/immutably on state.pojo.

const _filter = require("lodash/filter");
const { applyPatch } = require("makitso-prompt");
 
// available as `keyPressAutocomplete` but you'll likely want to build your own
function AutoComplete(choices) {
  return {
    keyPress: async function(state, press) {
      if (state.mode === "command") {
        let command = state.command;
 
        const matches = _filter(choices, choice => choice.startsWith(command));
 
        if (press.key && press.key.name === "tab" && matches.length === 1) {
          state.command = matches[0] + " ";
          state.cursorCols = null;
        } else {
          // state.pojo = applyPatch(state.pojo, { footer: matches.join(" ") });
          state.footer = matches.join(" ");
        }
      }
      return state;
    }
  };
}
 
const complete = AutoComplete(["abc1", "ab12", "abcdefg", "a123"]);
 
const prompt = new Prompt();
Object.assign(prompt, { keyPressers: [...prompt.keyPressers, complete] });
 
const command = prompt.start().then(console.log);