Is it good to learn Dart or i must stay with the basic javascript? [closed]

It all comes down to what you are trying to do and what your requirements are. I recommend you read some of the Dart vs. Javascript pages (to get both sides of the story) and ask yourself where you stand after reading those.

Here are some quick links from a Google of "Dart vs. Javascript". Please note that these links may not be balanced or even have very good reasons, but I hope they are enough to get you started. I highly recommend that you look for some more comparisons and do your own research on both sides of the issue:

Here's a pro-Dart page, but one that gives details on why the poster likes Dart:http://www.grobmeier.de/10-reasons-why-dart-is-cooler-than-javascript-03012012.html#.UL0kXuT7J8E

And here's a more pro-Javascript angle:http://www.quirksmode.org/blog/archives/2011/10/dart_or_why_jav.html

Again, don't take these links as instructions on whether you should or should not use Dart. Rather, read WHY each link supports one or the other then ask yourself if that reasoning applies to your case.

This talk where Google introduced Dart at the last Google I/O conference earlier this year might answer a bunch of your questions and considerations:

http://www.youtube.com/watch?v=bsGgfUreyZw

In short: It doesn't sound like Dart is at the point where it's really that useful yet. So one of the things you need to consider is: When do you need the tool by. If it's now, stay away from Dart (for now).

If you are interested in alternatives to coding in plain JavaScript, you should also check out the Google Web Toolkit. I have a feeling Dart might even be the evolution of GWT.

GWT is very mature, ready for action today, and uses Java for development, which, combined with Eclipse or IntelliJ delivers amazing productivity that I don't think is possible in JavaScript. Especially for complex applications that need to run cross-browser and actually be reasonably bug-free.

Here's a (pretty old, but) good intro to GWT as well, also from Google I/O (but 2008):

https://www.youtube.com/watch?v=nvti32k4xyU (replaced the link... this one is better)