html - how to change the background image of div using javascript?

Question

this is my code

<div style="text-align:center;">
  <div class="ghor" id="a" onclick="chek_mark()"></div>
  function call
</div>
<script type="text/javascript">
  function chek_mark(){
   var el= document.getElementById("a").style.background-image;
   if (el.url("Black-Wallpaper.jpg"))  
   {
     el.url = "cross1.png";
    }
    else if(el.url("cross1.png"))
    {
      alert("<h1>This is working too.</h1>");
     }
   }
</script>

here I want to change the background image using if else condition

this is the style-sheet
.ghor //this is the div class
{
    background-image: url('Black-Wallpaper.jpg');
    background-size: cover;
    border-radius: 5px;
    height: 100px;
    width: 100px;
    box-shadow: 2px 5px 7px 7px white;
    /*background-color: black;*/
    display:inline-block; 
}

i want change the background image of the 'div' which class is 'ghor'

Answer 1

Try this:

document.getElementById('a').style.backgroundImage="url(images/img.jpg)"; // specify the image path here

Hope it helps!