set background javascript code example

Example 1: javascript style background color

// change background color for specific id ..
function changebackground(){
	document.getElementById('id').style.backgroundColor = 'green' ; 
}
// change background color for whole body..
function changebackground(){
	document.body.style.backgroundColor = 'green';
}

Example 2: js background

document.body.style.background = "#f3f3f3 url('img_tree.png') no-repeat right top";

Example 3: set an attribute background image javascript

document.body.style.backgroundImage = "url('img_tree.png')";

Example 4: document.body.style.background

// Change the background color to red
document.body.style.backgroundColor = "red";

Example 5: set an attribute background image javascript

function bg() {

   var imgCount = 3;
   var dir = 'http://local.statamic.com/_themes/img/';
   // I changed your random generator
  	//floor: helps getting a random integer
   var randomCount = (Math.floor(Math.random() * imgCount));
   // I changed your array to the literal notation. The literal notation is preferred.
   var images = ['001.png', '002.png', '003.png'];
   // I changed this section to just define the style attribute the best way I know how.
   document.getElementById('banner').setAttribute("style", "background-image: url(" + dir + images[randomCount] + ");background-repeat: no-repeat;background-size: 388px 388px");
}
// Don't forget to run the function instead of just defining it.
bg();