In an external JavaScript file write code that, upon form submission, scans the list of courses for a match (case should be insensitive). If a match is found, change the div's background color to yellow. If no match is found, add the course name to the bottom of the course list (Hint: Read into DOM and Nodes). If the search field is left blank, return focus to the search field and display an alert box with an appropriate message. New searches must clear any yellow background before anything.