jQuery Performance.

Since jQuery is a 3rd party library, it won't be able to run at "native" speeds like your plain javascript will. To be completely honest though, jQuery wasn't designed with application performance in mind. jQuery has grown on the philosophy of writing less to accomplish more. More often than not, you see jQuery excel most on the front end.

This video actually shows a good example of when you should probably not use jQuery: the $.each() method. The standard "for" loop is a better choice for your algorithms, as it runs much more efficiently. Granted, you won't see the evidence of that so much in an array as small as the ones we're using here, but if you had to perform a lot of quick lookups, run through a 2-dimensional array, or do heavy math equations, you'd notice the difference, and so would your users.

Not to be one-sided, there are two benefits I can think of for using $.each(), rather than "for". First off, you don't have to worry about scope issues, since you're essentially passing everything in to a function. Also, like all things jQuery,an $.each() method can help minimize your code, and depending on the implementation, can make your code a little more elegant and readable.

Ultimately, it's good to know there's an alternative to the "for" loop, and if you're sticking to the front end, or smaller applications, you'll likely not notice a difference between the two.

jQuery is filled with random alternatives to normal syntax. Keep an eye out for these and always as yourself what your program's priorities are. It may be better suited to the standard, long-form javascript.

What do you mean, Hernán?