The goal was to make online calculator that will produce the same results calculations that there was alredy made in  spreadsheet. 

First of all I thought How I do that. It looked quite hard to code all non-transparent logic and data with different formulas that was already done  in xls file that I’ve got from my custumer. But what if just open xls(odf) file change some cells value (input  params )  and read the the result of calculations from others. This thought had crossed my mind. There sould be tools that could work with .xls or .odf files and I need a crossplatform one.  And I start looking up….

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Talking about Advanced JavaScript debugging.

First of all about tools. Currently, the most powerful debuggers are the Firebug extension in Firefox and the Opera Dragonfly debugger in Opera.
Firebug is well-known, userfriendly, and its more than enough in most situation. But from my own expierence, sometimes Dragonfly can help to debug code that has been “packed” and needs to be unpacked using eval(), when Firebug can’t. I was faced with such situation about half a year ago when I need to fix an application based on Dojo.

Now about techniques. Here is an particular interesting technique that I found from the article “Advanced debugging with JavaScript” :

…Debuggers for many other programming languages have a “watch” concept that can break into the debugger when a variable changes. Neither Dragonfly nor Firebug currently support “watch” but it’s easy to get the same effect by adding the following line of debugging code at the top of the source of the script you’re troubleshooting:
__defineSetter__('prop', function() { debugger; });
Using getters and setters can emulate “watch” functionality and help you set “smart” breakpoints.

A good news jQuery 1.3. released on January 14,2009. There are quit many changes and improvments. 

These three are very important as for me:

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Some notes from Original arctile by Jeff Cogswell

You couldn’t possibly know everything. Instead,  a good programmer knows where to quickly find the answers.

What is the difference between good programmer and superior programmer?

• be familiar with the information resources, especially the online documents, as well as any existing libraries and frameworks;
• not rolling their own classes and components when one already exists that does the job;
• be aware of the real issues that come up in a multiuser, high-performance system such as a Web server handling thousands or even millions of sessions a day

  How can you transform the good programmers into fantastic, amazing, awesome programmers? 

 Probably the single biggest issue that younger programmers overlook is the hidden complexity in today’s software systems.  With today’s multiuser Web sites, the biggest problems aren’t so much stress on memory and disk space, since typically the software will be running on large servers with a team of IT people making sure there’s plenty of both. Instead, today the problems come more from multiple users trying to do the same thing simultaneously.  The developers must be trained in how to write code that handles such situations correctly so the system doesn’t crash.  

       You  can teach your team to not allow common bugs in the first place and have to.