How do I get javascript to build a url from vars

function search() {
    var myRootSite = 'www.mysite.org/sermons?category=';
    var myNewTitle = document.getElementById('myTextField').value;
    var mySpeaker = document.getElementById('mySpeaker').value;
    var myService = document.getElementById('myService').value;
    var mySeries = document.getElementById('mySeries').value;
 
    var myBook = document.getElementById('myBook').value;
    var myDate = document.getElementById('myDate').value;
 
    if (myNewTitle == 0 && mySpeaker == 0 && myService == 0 && mySeries == 0 && myBook == 0 && myDate == 0) {
        alert('Please enter some search criteria');
        return;
    }
 
    var title = document.getElementById('title');
    title.innerHTML = mySpeaker;

    var valuesArr = [ myNewTitle, mySpeaker, myService, mySeries, myBook, myDate ]; // put the items in an array
    var valuesStr = valuesArr.join("+"); // join them
    var URL = myRootSite + valuesStr; // concatenate them to myRootSite
}