Color vision deficiency
From JSXGraph Wiki
JSXGraph can give a rough impression about how color blind people see your work. It is possible to emulate three types of color vision deficiency: Protanopia, Deuteranopia, and Tritanopia.
Consider this geometric construction from the Euler line example.
Code
// To enable color vision deficiency emulation just use
board.emulateColorblindness(deficieny);
// where deficieny is a string equal to either 'protanopia', 'deuteranopia' or 'tritanopia'. To disable it use
board.emulateColorblindness();
// without any parameters.