Content from tayfunsen.com:
If you are programming in JavaScript, the odds are that you come from C/C++/Java background and have been bitten by the web development bug. This might cause a couple of problems however, mostly because JavaScript is "Lisp in C's Clothing". So you might find yourself a little disoriented with the familiar syntax and sometimes very unintuitive execution. One thing that is not quite so easy to understand is the fact that functions are first class in JavaScript and that they do create closures. Couple that with lexical scoping and you can get some really unexpected results.
Connected to the concept of functions being first class is the notion of variable hoisting. Dictionary definition of "hoisting" is lifting or raising something up. And this exactly what JavaScript engines do. Any variable that is declared (be it initialized to a primitive data type, an object or even a method) anywhere in a function will actually be run as if they are declared in the beginning of that function. That is, they are raised to the top of the scope they are in. Initializations for that variable will not run however, since this is not what you normally expect, and because it would have caused rather unexpected run time peculiarities.
No comments:
Post a Comment