Why I don’t use javascript frameworks

Let me summarize:

I don't like learning to use other people's code. I prefer to force my coworkers to learn mine.

But never fear - I'm sure this guy's undocumented, buggy, slow, half-implemented version of half of jQuery core is every bit as fun to use as the real thing. And so flexible!

[Note: That last paragraph may be harsher than this poor guy deserves, but I can't resist paraphrasing Greenspun. Who does not tend to mince words.]

Not using existing JS frameworks is a terribly stupid idea. Unless of course you're building your own framework and are willing to test it across all browsers, etc to make sure it all actually works.

I have used jQuery, Dojo and Prototype/Scriptaculous in several projects and there is just no way in hell I am going to duplicate all the programming effort that went into getting all the API functions working in every browser.

Never mind the documentation efforts, module system (hello Dojo!), the built-in compression tools, etc.

For a page that just needs one or two JS routines I'll code it up myself, but for more complex requirements I'll take a framework any day of the week.

Do you really want to figure out why your "setOpacity" function isn't working on Safari Mobile?

Flexibility

Prototype and JQuery are flexible enough to stay out your way.

Developer background

"produce hand made code"

Unnecessary coding instead of using the code that was already developed, designed and tested by community

Insight

"I know exactly what is behind methods I use"

These frameworks are 100% open, go ahead and look inside, you'll see how JS gurus are doing it.

Accessibility

"keeping relatively low size of a page"

Frameworks mentioned are small and lightweight enough. Prototype.js weight is 124 kb (unpacked), consider browser caching (use google access), and this argument won't be serious anymore.