uniqueNumber.js

// The ID() function will return a unique number every time you call.
// Code is from http://qnimate.com/generate-unique-number-in-javascript/
function uniqueNumber() {
    var date = Date.now();
    
    if (date <= uniqueNumber.previous) {
        date = ++uniqueNumber.previous;
    } else {
        uniqueNumber.previous = date;
    }

    return date;
}

uniqueNumber.previous = 0;

function ID(){
  return uniqueNumber();
};