I’m a big proponent of prototyping charts.
Getting a feel for D3, NVD3, or C3 is invaluable for understanding what is possible using the charting libraries (and to have empathy for the developers you work with who have to chop away at the mess) is key to basing your designs on realistic assumptions.
Not to mention data understanding. You never know what your data will look like, or how understandable your data will be until you visualize it yourself.
But sometimes your deliverable is a high-fidelity design – you need to pull that chart out of the web somehow t
The best way I’ve found is to use the SVGCrowbar bookmarklet. It exports SVGs which you can open in Illustrator and place in your designs.
Have a look: