Including a variable into an url string in javascript

I’m wondering how to insert the imageId number into the url string, I got confused when there’s a string inside a string.

const imageId = 13935764;

switchBackground.onclick = function(){
  setbg.style.backgroundImage = "url('https://images.pexels.com/photos/'+imageId+'pexels-photo-13366951.jpeg?cs=srgb&dl=pexels-kwnos-iv-13366951.jpg&fm=jpg')";
}