          if (graph_type === 'bar-chart') {
                    document.getElementById("rendering_parameters").innerHTML = 'Axe des x : <select name="x_field" \
                    id="x_field-select" oninput="render ()"></select> <button \
                    id="add_render_field" onclick="addRenderField ()">+</button>';
                    fieldOptions ([document.getElementById("x_field-select")]);
                } else if (graph_type === 'curve') {
                    document.getElementById("rendering