Grab's the value of url parameter "employer=" and sets the value into the marketo form field "Company" of the landing page. Also, has encoding special characters.
Example URL: http://resources.glassdoor.com/lp-us-ebook-clone.html?employer=Hewlett%20Packard%20APAC
MktoForms2.whenReady( function(form) {
var urlParams = new URLSearchParams(window.location.search);
var employerName = urlParams.get('employer');
form.vals( {"Company":employerName} );//set value in Employer field
})