I was trying to create a simple AJAX request which returns some data from a database. My function is mentioned below:
function AJAXrequest(url, postedData, callback) { 
    $.ajax({ 
            type: 'POST', 
              url: url, 
              data: postedData, 
              dataType: 'json', 
              success: callback 
      }); 
}
Here's where I call it, providing the required parameters:
AJAXrequest('voting.ajax.php', imageData, function(data) { 
// function body 
});
Yet, the callback does not run, and instead I get an error in the console:
TypeError: $.ajax(...) is not a function.
I want to know the reason why and how do I go about this?