Douglas Crockford's book "JavaScript: The Good Parts," is one of the best selling JavaScript books of all time and is only 176 pages long. For most developers, there's an tacit belief that the rest of JavaScript falls under "bad," especially when comparing that to the 900 pages of "JavaScript: The Definitive Guide" There are websites dedicated to these list of language mis-features and anti-patterns, and dozens of blog posts about how to avoid the "bad" in your own code.
I don't think that these most of these things are actually "bad". In their day to day, developers don't need to worry about all of these smaller issues. Chances are, a JavaScript developer has encountered these difficult issues, learned the solution, and then immediately absorbed the concepts.
I'm going to explain to you, the real "bad" parts of the language. These are at least three JavaScript language features that are the most likely to trip up a JavaScript developer. Once you innately understand these three issues, you will become significantly more productive in JavaScript, and will be a lot less confused when reading through large JavaScript code bases.
I'll be walking you through at least three concepts within JavaScript language semantics:
- What on earth does "this" mean, and in what context does its meaning change?
- How does prototypal inheritance work? What is hoisting?
- Why do I care what a function expression or function declaration is?
About John Paul
John K. Paul is the lead technical architect of Conde Nast's platform engineering team and former lead front end software engineer at TheLadders.com. He is a contributor to numerous open source projects including learn.jquery.com. He has spoken to various startups around NYC about front end development, and scalable engineering practices, in particular, unit testing javascript. Additionally, he has taught JavaScript and jQuery fundamentals to teams throughout the NYC area.