nodejs/lib/internal/main/repl.js

'use strict';

// Create the REPL if `-i` or `--interactive` is passed, or if
// the main module is not specified and stdin is a TTY.

const {
  prepareMainThreadExecution
} = require('internal/bootstrap/pre_execution');

const {
  evalScript
} = require('internal/process/execution');

const console = require('internal/console/global');

const { getOptionValue } = require('internal/options');

prepareMainThreadExecution();

markBootstrapComplete();

if (process.env.NODE_REPL_EXTERNAL_MODULE) {
  require('internal/modules/cjs/loader')
    .Module
    ._load(process.env.NODE_REPL_EXTERNAL_MODULE, undefined, true);
} else {
  // --input-type flag not supported in REPL
  if (getOptionValue('--input-type')) {
    // If we can't write to stderr, we'd like to make this a noop,
    // so use console.error.
    console.error('Cannot specify --input-type for REPL');
    process.exit(1);
  }

  console.log(`Welcome to Node.js ${process.version}.\n` +
    'Type ".help" for more information.');

  const cliRepl = require('internal/repl');
  cliRepl.createInternalRepl(process.env, (err, repl) => {
    if (err) {
      throw err;
    }
    repl.on('exit', () => {
      if (repl._flushing) {
        repl.pause();
        return repl.once('flushHistory', () => {
          process.exit();
        });
      }
      process.exit();
    });
  });

  // If user passed '-e' or '--eval' along with `-i` or `--interactive`,
  // evaluate the code in the current context.
  if (getOptionValue('[has_eval_string]')) {
    evalScript('[eval]',
               getOptionValue('--eval'),
               getOptionValue('--inspect-brk'),
               getOptionValue('--print'));
  }
}