Sharepoint - Get the id value from the page url

you can use SharePoint’s GetUrlKeyValue() function to get item id. Example:

var itemId = GetUrlKeyValue("ID", false, location.href);

Use the following javascript function :

function getParameterByName(name) {  
    name = name.replace(/[\[]/, "\\[").replace(/[\]]/, "\\]");
    var regex = new RegExp("[\\?&]" + name + "=([^&#]*)"), results = regex.exec(location.search);
    return results == null ? "" : decodeURIComponent(results[1].replace(/\+/g, " "));
}
var prodId = getParameterByName('prodId');