How do I implement tab completion in node.js shell?

I was looking for this feature in node.js and I haven't found it.

Can I implement it myself? As far as I know, node.js doesn't load any file at it's startup (like Bash does with .bashrc) and I haven't noticed any w开发者_运维知识库ay to somehow override shell prompt.

Is there a way to implement it without writing custom shell?

You could monkey-patch the REPL. Note that you must use the callback version of the completer, otherwise it won't work correctly:

var repl = require('repl').start()
var _completer = repl.completer.bind(repl)
repl.completer = function(line, cb) {
  // ...
  _completer(line, cb)
}

Just as a reference.

readline module has readline.createInterface(options) method that accepts an optional completer function that makes a tab completion.

function completer(line) {
  var completions = '.help .error .exit .quit .q'.split(' ')
  var hits = completions.filter(function(c) { return c.indexOf(line) == 0 })
  // show all completions if none found
  return [hits.length ? hits : completions, line]
}

and

function completer(linePartial, callback) {
  callback(null, [['123'], linePartial]);
}

link to the api docs: http://nodejs.org/api/readline.html#readline_readline_createinterface_options

You can implement tab functionality using completer function like below.

const readline = require('readline');

/*
 * This function returns an array of matched strings that starts with given
 * line, if there is not matched string then it return all the options
 */
var autoComplete = function completer(line) {
  const completions = 'var const readline console globalObject'.split(' ');
  const hits = completions.filter((c) => c.startsWith(line));

  // show all completions if none found
  return [hits.length ? hits : completions, line];
}

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  completer: autoComplete
});

rl.setPrompt("Type some character and press Tab key for auto completion....\n");


rl.prompt();
rl.on('line', (data) => {
  console.log(`Received: ${data}`);
});

Reference : https://self-learning-java-tutorial.blogspot.com/2018/10/nodejs-readlinecreateinterfaceoptions_2.html