Grapher2D.js is a javascript library based off of my Grapher2D application that is written in C. Just like the desktop applicaation, Grapher2D.js uses OpenGL to quickly graph complex mathematical functions onto the screen.
Grapher2D.js currently uses WebGL 2.0 with the EXT_color_buffer_float extension. WebGL 1.0 functionality is planned for browers that do not support the newer standard, but implicit graphing is unlikely to be implemented.