Ask HN: Why there is no good Graph Visualization Library in Javascript?

What kind of graphs do you mean? If you're talking about charts, not graphs with nodes and edges, then there are a few:

Thumbs up for highcharts. Easy to use and really flexible.

Which libraries did you check, that did not fulfill your requirements, and why?

I've used both gRaphael (http://g.raphaeljs.com/) and jqPlot (http://www.jqplot.com/) before, and found both to be at least decent (though, I had a few issues with jqPlot, but switching to gRaphael solved those).

There's also Protovis (http://vis.stanford.edu/protovis/) which has been used for graph visualization.

http://code.google.com/p/flot/

http://smoothiecharts.org/