"Learning Node JS" example - 'The super constructor to "inherits" must not ' +' - node.js

Question

I'm fowolling along to exercise in the O'Reilly "Learning Node JS" book and I've run into an unrunnable example. My code is as follows:
"use strict";
var util = require('util');
var eventEmitter = require('events').eventEmitter;
var fs = require('fs')
function InputChecker(name, file) {
this.name = name;
this.writeStream = fs.createWriteStream('./' + file + '.txt',
{'flags': 'a',
'encoding': 'utf8',
'mode' : 0o666});
};
util.inherits(InputChecker, eventEmitter);
InputChecker.prototype.check = function check(input) {
let command = input.trim().substr(0,3);
if (command == 'wr') {
this.emit('write', input.substr(3, input.length));
} else if (command == 'en:') {
this.emit('end');
} else {
this.emit('echo', input);
}
};
let ic = new InputChecker('Shelley', 'output');
ic.on('write', function(data) {
this.writeStream.write(data, 'utf8');
});
ic.on('echo', function(data) {
process.stdout.write(ict.name + ' wrote ' + data);
});
ic.on('end', function() {
process.exit();
});
process.stdin.setEncoding('utf8');
process.stdin.on('readable', function() {
let input = process.stdin.read();
if (input != null)
ic.check(input);
});
The error is:
[user#MacBook-Pro NodeJS]$ node fileevent.js
util.js:957
throw new TypeError('The super constructor to "inherits" must not ' +
^
TypeError: The super constructor to "inherits" must not be null or undefined
at Object.exports.inherits (util.js:957:11)
at Object.<anonymous> (/Users/user/Documents/NodeJS/fileevent.js:15:6)
at Module._compile (module.js:570:32)
at Object.Module._extensions..js (module.js:579:10)
at Module.load (module.js:487:32)
at tryModuleLoad (module.js:446:12)
at Function.Module._load (module.js:438:3)
at Module.runMain (module.js:604:10)
at run (bootstrap_node.js:389:7)
at startup (bootstrap_node.js:149:9)`
Any help is appreciated! TIA!

Answer 1

Your mistake is here:
var eventEmitter = require('events').eventEmitter;
The EventEmitter object is title-case, since it is a class name. It could be corrected by rewriting it as:
var EventEmitter = require('events').EventEmitter;
but that is the obsolete way of importing the EventEmitter class for Node.js v0.10.x and earlier, which is only supported now for backwards compatibility. The recommended way to import it is:
const EventEmitter = require('events');
and refactor the rest of your references from eventEmitter to EventEmitter in order to follow the convention of naming classes with a capital letter.