https://www.npmjs.com/package/steem
https://github.com/adcpm/steem
<script src="./steem.min.js"></script>
<script>
steem.getAccounts(['ned', 'dan'], function(err, response){
console.log(err, response);
});
</script>
https://github.com/adcpm/steem/tree/master/doc
If you need more informations, i'm available on the chat with the id @fabien