gistfile1.js

String.prototype.visualLength = (function() {
    var that = this,
        ruler = document.getElementById('ruler');
    if (!ruler) {
        ruler = document.createElement('span');
        document.body.appendChild(ruler);
    }
    ruler.style.visibility = 'hidden';
    return function () {
        ruler.innerHTML = that;
        return ruler.offsetWidth;
    };
})();