OpenLayers 4 - Change Text BackColor

Question

I want to change my text backcolor.

        new ol.style.Style({
        text: new ol.style.Text({
            text: marker_name,
            fill: new ol.style.Fill({
                color: '#fff'
            })
        })   
     })

"fill" property change text color.
I search from OpenLayers v4.0.1 ol.style.text but I did not find propery for this.

---

You think draw a shape under the text like this

 new ol.style.Style({
        image: new ol.style.RegularShape({
            fill: fill,
            //stroke: stroke,
            // offsetY: -25,
            points: 4,
            radius1: 30,
            radius2:10,
            angle: Math.PI / 4
        }),
        text: new ol.style.Text({
            text: marker_name,
            fill: new ol.style.Fill({
                color: '#fff'
            })
        })

But OpenLayers v4 can't draw rectange in style. For this issue you can look that.

Answer 1

I don't really understand why OL can't draw rectangle in style so, simply I tried to make rectangle behind text style like:

var style =  new ol.style.Style({
  image: new ol.style.RegularShape({
    fill: new ol.style.Fill({color: 'red'}),
    points: 4,
    radius: 15,
    angle: Math.PI / 4
  }),
  text: new ol.style.Text({
    text: 'abc',
    fill: new ol.style.Fill({
      color: '#fff'
    })
  })
});

codepen here
this example's from OL 'regular shape' example