How much JavaScript do you need for an entry-level job?
Jeff Cogswell recently posted some guidelines.
The absolute basics
- Variables
- Functions
- The difference between null and undefined
- And so on
Beginner’s List
- Know the different ways to create objects, such as using the “new” keyword, as well as just declaring an object (such as ‘x = {a:1, b:2};’).
- Know what a prototype is, what the “this” variable does, and how to use both.
- Know the difference between a list and an object (and how a list is technically both, and can be used as both).
- Know that functions are objects that can be passed as parameters into other functions and returned from other functions.
- Know what closures are and how to use them. This might seem like an advanced topic, but when working with functions returning functions, it’s easy to introduce bugs if you’re not careful.
- Know how to use functions such as the list’s map and filter functions. With this in mind, I encourage you to read this specification and learn the methods available on all types of objects.
- Understand the built-in objects (they’re constructors!) and how to use them, including Function and Array (with capital F and A).
- Know your way around the developer command line and debugger. All the major browsers provide these now.
Document Object Model
The DOM (Document Object Model) is the browser’s representation of a Web page. Vital aspects include:
- Accessing the DOM directly from JavaScript. For example, know how to locate elements through calls such as getElementById, getElementsByClassName, getElementsByTagName, and so on. Also know how to use the newer selector methods: querySelector, querySelectorAll.
- Accessing the DOM using jQuery. Again, jQuery isn’t part of JavaScript, but a lot of employers expect you to know it. Know the difference between $(‘a’) and $(‘.a’). A simple dot changes everything.
- Understand the global object, how the browser provides the global object, and how you access it through your JavaScript programming. (Answer: The browser provides the window object (lowercase w) as the global object.)
- Understand why the browser is the service implementing the global object and what happens when you move JavaScript code outside of the browser, such as to Node.js.
A lot of documentation presents the DOM API using what looks like C-language interfaces. That’s because under the hood, the objects likely are C objects. You access these objects through your JavaScript code. For example, when you call getElementById, you get back an element. But under the hood, that object is a C object with properties and methods.
Advanced
- Know how to call bind, call, and apply on a function, what the differences are, and why you would need to use them.
- Know the different ways to create objects, including Object.create, and when you’ll need the hasOwnProperty method.
- Know the different ways of implementing object-oriented programming, especially inheritance.
- Know what promises are, and learn two important asynchronous libraries: async and Q. They’re used a great deal in server-side Node.js programming, but can also be a huge benefit in browser programming.
- Learn server-side Node.js programming. It will really force you to become a JavaScript guru.
Source: JavaScript You Need to Know For a Job
Via Slashdot: How Much JavaScript Do You Need To Know For an Entry-Level Job?
This comment from Slashdot has good advice for the aspiring programmer:
If you want an entry level programming job and don’t have any experience, you’d had better made something non-trivial on your own time that you can show in an interview and explain the code. If I’m skimming your code and I see you picked a certain data structure or implemented a algorithm when there is more than one way to do it, you should be able to explain your reasoning for coding it the way you did. Also make sure you learn at least the basics of one of the popular frameworks and use it in your demo.
So make a Javascript web app, or something on the server side with a free or low cost hosting account. Make it functional, make it as bug proof as you can, make the code clean and easy to read, and be prepared to show it to a skeptical audience. Think of your interview as an audition and your code as the music you’re going to play.
If you can’t make something to show, you don’t know enough Javascript yet.
[Source]
