Line
From JSXGraph Wiki
Construction of a line
A line needs two points. Lets construct two points "A" and "B".
var b = JXG.JSXGraph.initBoard('jxgbox', {originX: 200, originY: 100, unitX: 50, unitY: 50});
var p1 = board.createElement('point',[-1,1], {name:'A',style:6});
var p2 = board.createElement('point',[2,-1], {name:'B',style:6});