AJAX and JSON guide for beginners

ajax-json.html

<button type="button" onclick="getJSON()">Get the users</button>
<table id="users"></div>

<script>
function getJSON() {
    var ajax_req = new XMLHttpRequest();
    ajax_req.open('GET', 'https://api.github.com/users', true);

    ajax_req.onload = function() {
        //status 200 means everything is ok
        if (this.status === 200) {
            var json = JSON.parse(this.responseText);
            var row = '';
            for (i in json) {
                row += '<tr><td>' + json[i].login +
                    '</td><td><img src="' +
                    json[i].avatar_url + '</td></tr>';
            }
            document.getElementById('users').innerHTML = row;
        }
    }

    ajax_req.send();
}
</script>