var custom_elems = ['span','div','p','ul','li'];
var rand = custom_elems[Math.floor(Math.random()*custom_elems.length)];
var para = document.createElement(rand);
para.style.display = "none";
var str = randomString(12);
para.classList.add(randomString(12));
var node = document.createTextNode(randomString(88));
para.appendChild(node);
var element = document.getElementById("app");
element.appendChild(para);
function randomString(length) {
var text = "";
var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
for(var i = 0; i < length; i++) {
text += possible.charAt(Math.floor(Math.random() * possible.length));
}
return text;
}