MY CODES

BODY BACKGROUND SLIDER-3

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<style>
body {background:#115599;background-image:url(https://i.imgur.com/VZcildl.jpg);background-attachment:fixed;background-position:left top;background-repeat: no-repeat;
background-size:1600px 900px;} 
#b1 {background-image:url(https://i.imgur.com/UKrGMoA.jpg);}
#b2 {background-image:url(https://i.imgur.com/Jrw6vMy.jpg);}
#b3 {background-image:url(https://i.imgur.com/1OB6MoL.jpg);}
#b4 {background-image:url(https://i.imgur.com/aXZruOI.jpg);}
#b5 {background-image:url(https://i.imgur.com/2t5y2Tc.jpg);}
#b6 {background-image:url(https://i.imgur.com/2eSYtrp.jpg);}
#b7 {background-image:url(https://i.imgur.com/seHWgNP.jpg);}
#b8 {background-image:url(https://i.imgur.com/b7cGD5L.jpg);}
#b9 {background-image:url(https://i.imgur.com/CHqxCkI.jpg);}
#b10{background-image:url(https://i.imgur.com/LRmccLf.jpg);}
#b11 {background-image:url(https://i.imgur.com/4hHNp8t.jpg);}
#b12 {background-image:url(https://i.imgur.com/EdBhTYQ.jpg);}
#b13 {background-image:url(https://i.imgur.com/HjoSwfe.jpg);}
#b14 {background-image:url(https://i.imgur.com/phbIVY1.jpg);}
#b15{background-image:url(https://i.imgur.com/VZcildl.jpg);}
</style>      
<script>  
function run(interval, frames) {
var int = 1;
function func() {
document.body.id = "b"+int;
int++;
if(int === frames) {int = 1;}}
var swap = window.setInterval(func, interval);}
run(4000, 15); // milliseconds, frames
</script>