jQuery POST Boilerplate-ish.

$.post("[script URL]", {[variableName]:[variableValue], [variableName]:[variableValue]},
    function(data) {
        if (data["longerThan512"] == true) {
            // ask(...) or w/e.
        }
    }, "json");

// Script returns JSON with a variable "longerThan512" - change if you wish.
// Takes whatever variables, as defined above.