JavaScript - ga-dc/glossary GitHub Wiki

  • AJAX - (asynchronous JavaScript and XML) is a set of techniques for asynchronous data requests (occurring in the background) which depend on the XMLHttpRequest Object. AJAX allows us to create dynamic applications that respond to user input without page reloads. This technology has lead to the immersive feel of modern web apps. More on the exciting history here.
  • Asynchronous - When your browser/server runs "listens" for some event before running a piece of code. (As opposed to "synchronous"). Such events may be a "success" message being returned from an API, or a click event, or a certain amount of time passing (for, say, a clock app).
  • Callback - A method that is passed as an argument to another method, and then called from inside that second method. This is useful for keeping your code a collection of neat methods rather than a huge "plate of spaghetti". It's essential for "asynchronous" code.
  • Closure
    • A special kind of object that combines two things: a function, and the environment in which that function was created. The environment consists of any local variables that were in-scope at the time that the closure was created.
  • Node(.js) - a lightweight runtime environment that enables server-side programming in JavaScript.

"Yes, JavaScript is not equipped to deal with operating system-level sockets and network connectivity. But Node isn’t written in JavaScript; it’s written in C, a language perfectly capable of doing the grunt work and heavy lifting required for networking. JavaScript is perfectly capable of sending instructions to a C program that can be carried out in the dungeons of your OS. In fact, JavaScript is far more accessible than C to most programmers — something worth noting now, and that will come up again and again in the reasons for looking seriously at Node. [T]he big news here is that Node is a program that you feed JavaScript. What Node then does with that JavaScript isn’t worth much ink; to some degree, just accept that what it does, it does. This frees you up to write JavaScript, not worry about learning C. Heck, a big appeal to Node is that you can actually write a server without worrying about C. That’s the point." - Brett McLaughlin

  • Synchronous - When your browser/server runs code in the order it's written (line 1, line 2, line 3...), this is called "synchronous". (As opposed to "asynchronous.")