var microsofts = $("ul[data-group='Companies']").find(" li[data-company='Microsoft']"); //Get all elements with data-company="Microsoft" below "Companies"
console.log(microsofts.html()); // Microsoft
<ul data-group="Companies">
<li data-company="Microsoft">Microsoft</li>
<li data-company="Google">Google</li>
<li data-company="Facebook">Facebook</li>
</ul>