Extract Classes from html string

extactclassesfromhtml.js

var str = 'bla<p class="c1 c2">blabla<button></button><div id="bla" class="  c1    c3 "></div>';
var classes=getHTMLclasses(str);
console.log(classes);


function getHTMLclasses(html) {
    // get all unique css classes in html into dict
    var classRegexp = /class=['"](.*?)['"]/g;
    var dict = [];
    var m;
    while ((m = classRegexp.exec(html))) 
    {
        var classes=m[1].replace(/\s+/g, ' ').trim();
        classes.split(" ").forEach(function(item) {
            dict[item]=true;
        });
    }

    // convert dict to arr
    var arr=[];
    for (var key in dict) arr.push(key);

    return arr;
}