Calculate Time Difference in between clicks of two buttons using JS

Question

I have two asp.net buttons and i want to calculate the time difference in between the clicks of the buttons using JS

Button 1 - Start
Button 2 - Next

First I got the current time on the click of the "start" button in getStartTime() function. and similarly for the second button in getEndTime() function.

For calculating the time difference I use another function calculateDifference() and call the above functions. I want to calculate the difference after the "Next" button click. The problem is getStartTime() is calculating the current time every time. How can

I store the time of button click in a variable and return it to another function?

var startTime, startHour, startMin, startSec, endTime, endHour, endMin, endSec, diffTime, stTime, etTime;

//To Get the click time of Start Button(btnStart_OnClick)
function getStartTime() {
  startTime = new Date();
  startHour = startTime.getHours();
  startMin = startTime.getMinutes();
  startSec = startTime.getSeconds();
  if (startHour > 0) {
    startHour = startHour * 3600;
  }
  if (startMin > 0) {
    startMin = startMin * 60;
  }
  stTime = startHour + startMin + startSec;
  return stTime;
}
//To get the click time of Next Button
function getEndTime() {
  endTime = new Date();
  endHour = endTime.getHours();
  endMin = endTime.getMinutes();
  endSec = endTime.getSeconds();
  if (endHour > 0) {
    endHour = endHour * 3600;
  }
  if (endMin > 0) {
    endMin = endMin * 60;
  }
  etTime = endHour + endMin + endSec;
  return etTime;
}

function calculateDifference() {
  var start = getStartTime(); // On calling this function, current date is returned instead of the click time of 'Start' button
  var end = getEndTime();
  var diff = end - start;
  return diff;
}
//Button Next_OnClick
function newTimeLeft() {
  var difference = calculateDifference();
  var newTimeLeft = 1800 - difference;
  if (newTimeLeft > 0) {
    javascript_countdown.init(newTimeLeft, 'javascript_countdown_time');
  }
}

Answer 1

If you need time differences between two button clicks you better keep track of the two timestamps. Then differentiate between two I guess this should work -

let startTime, endTime;

function getStartTime() {
    startTime = new Date().getTime()
}

function getEndTime() {
    endTime = new Date().getTime()
}

function calculateDifference() {
    return startTime - endTime;
}

Calling calculateDifference() will return the time difference in milliseconds. Rest is up to you.

Hope this helps.