node.js parsing tags in html

I am trying to parse for a specific tag inside 2 websites. I need to do that in an async way but to display the results to the user at the end. I tried using htmlParser2 but I am not using it correctly. For example how can I parse all the h2 tags from the html... Here is a code I was trying before:

var htmlparser = require('htmlparser2');

var parser = new htmlparser.Parser({
    onopentag: function(name, attribs){
        if(name === "h2"){
            // 
        }
    },
    ontext: function(text){
            // 
    },
    onclosetag: function(tagname){
        if(tagname === "h2"){
            //
        }
    }
});

parser.write(html_txt);
parser.end();

I am quite new to node.js so any help will be more than great. Thanks