Texts

The underlying JavaScript code

    var brd = JXG.JSXGraph.initBoard('jxgbox',{boundingbox: [-1,10,7,-1], axis:false, keepaspectratio:false});

    // Vertical line at x=3
    var A = brd.create('point', [2, 5], {strokeWidth:1, dash:2});  
    brd.create('text', [3, 8, function () { return 'X(A) = ' + A.X(); }]);

    brd.on('update', function () {
        document.getElementById('out').innerHTML = 'X(A) = ' + A.X();
    });

    <div id="out"></div>