Have question about jquery control - do you know where i can find (for free if it`s possible) radar jquery control that will have opportunity setup gradient for line?
It should looks like on picture here
Thanks a lot.
D3 is a good charting library. However it won't come with pre-made charts. You will have to do some work on your end. But on the plus side, it is free.
https://github.com/mbostock/d3/wiki/Gallery and http://graves.cl/radar-chart-d3/
Other Options:
Gradient Line Option for D3:
D3 uses SVG. So you could modify the fill with a gradient image. See here on how to change the fill. Fill SVG path element with a background-image