JavaScript code snippet to get list of all CSS class names in HTML file

get-all-class-names.js

var used = [];
var elements = null;
var skipelements = [
	'nav'
];

//get all elements
if (typeof document.getElementsByTagName != 'undefined') {
    elements = document.getElementsByTagName('*');
}

if (!elements || !elements.length) {
    elements = document.all; // ie5
}

//loop over all element
for (var i = 0; i < elements.length; i++){

    //loop over element's classes
    console.log(elements[i].className);
    var classes = elements[i].className.split(' ');
    for (var j = 0; j < classes.length; j++) {

        var name = classes[j];

        //add if not exists
        if (name.length > 0 && used.indexOf(name) === -1 && skipelements.indexOf(name) === -1) {
            used.push(name);
        }
    }
}
var block = document.createElement("pre");
block.innerHTML = '.'+used.join('{}\n.')+'{}'; 
document.getElementsByTagName('body')[0].appendChild(block);