I know that it is possible to make a line or polygon with dashed stroke. It can be done with the following way, for example:
var myStyle = new ol.style.Style ({ stroke: new ol.style.Stroke({ color: 'rgba(221, 99, 0, 0.5)', width: 3, lineDash: [40,10] //
var myStyle = new ol.style.Style ({ stroke: new ol.style.Stroke({ color: 'rgba(221, 99, 0, 0.5)', width: 3, lineDash: [40,10] //