function onInit(){
var images = Array("images/proprepair.jpg","images/maintenance.jpg","images/clients.jpg");

var repair = document.getElementById("imagerepair");
var maintain = document.getElementById("imagemaintain");
var build = document.getElementById("imagebuilding");


repair.setAttribute("src",images[randNo()]);
maintain.setAttribute("src",images[randNo()]);
build.setAttribute("src",images[randNo()]);

}

function randNo(){

var randomnumber=Math.floor(Math.random()*3);

return randomnumber;

}

window.onload = onInit;