create attribute and describe it in javascript code example

Example 1: javascript create element with attributes

var element = document.createElement("span");
element.setAttribute("style", "color: red");
document.body.appendChild(element);

Example 2: put new attribute on html tag using javascript

// Here's what you do for the style attribute
span.setAttribute("style", "width:110%;float:center;left-margin:-10px;top-margin:-10;");