Finds the width in ems of any string

getEmWidth

  // Finds the width in ems of any string
// Useful for finding out how wide elements set on the page in ems will be in pixels
  function getEmWidth(chars){
    var p = document.createElement("span");
    p.innerHTML = chars;
    document.body.appendChild(p);
    var width = p.getBoundingClientRect().width;
    document.body.removeChild(p);
    return width;
  }