Ajax

var employees = JSON.parse(xhr.responseText); /* responseText is the text that came in the ajax call. You are just parsing that content into an object. */
var statusHTML = '<ul class="bulleted">'; // This is the element created to contain the list of employees names.

// Loop trought all the employees stored in the employees variable.

/* If the employee is at the office then concatenate this string to the statusHTML variable. (It will create a list element with the class 'in' the office. */
statusHTML += '<li class="in">';
/* If the employe is not at the office then concatenate this string to the statusHTML variable.
statusHTML += '<li class="out">';

/* Now the statusHTML variable should look something like this
<ul class="bulleted">
<li class="in"> or <li class="out">
*/

// Add the employee name to the statusHTML string
statusHTML += employee[i].name;
statusHTML += '</li>';

statusHTML += '</ul>';

/* If you have 3 employees the result HTML should look something like this
<ul class="bullted">
<li class="in"> or <li class="out">
employee[0].name
</li>
<li class="in"> or <li class="out">
employee[1].name
</li>
<li class="in"> or <li class="out">
employee[2].name
</li>
</ul>
*/