Untitled

Center point on html quadratic curve
x(t) = (1-t)^2 * x1 + 2 * (1-t) * t * x2 + t^2 * x3
y(t) = (1-t)^2 * y1 + 2 * (1-t) * t * y2 + t^2 * y3

function _getQBezierValue(t, p1, p2, p3) {
    var iT = 1 - t;
    return iT * iT * p1 + 2 * iT * t * p2 + t * t * p3;
}

function getQuadraticCurvePoint(startX, startY, cpX, cpY, endX, endY, position) {
    return {
        x:  _getQBezierValue(position, startX, cpX, endX),
        y:  _getQBezierValue(position, startY, cpY, endY)
    };
}