How can I add minutes to a pomodoro clock?

Question

I am a JS novice trying to build a pomodoro clock with minimal functionality. While I have the basic countdown working, I am having difficulties implementing the 'add additional minute' functionality to the timer.

So far, I have this pasted immediately after my variables declaration:

// Add more minutes to timer
add.addEventListener("click", addMin);

function addMin() {
  mins += 1;
  timer.textContent = mins + ":" + "0" + currentSecs;
}

While this adds the minutes prior to countdown, it does not update the actual countdown minutes. Where have I gone wrong? A fresh pair of eyes on this issue would be greatly appreciated (and save a few kittens..)

I have added the HTML and JS code below:

var timer = document.getElementById("timer"),
  button = document.getElementById("button"),
  add = document.getElementById("add"),
  minus = document.getElementById("minus"),
  numOfPomodoros = 0;

// Variables for the Countdown to Work:
var mins = 25,
  secs = mins * 60,
  currentSecs = 0,
  currentMins = 0,
  comingOffBreak = false;


button.addEventListener("click", startCountdown);

function startCountdown() {
  setTimeout(countdown, 500);
}

function countdown() {

  currentMins = Math.floor(secs / 60);
  currentSecs = secs % 60;

  if (currentSecs <= 9) {
    // Add an extra zero to the seconds in order to make it look more like a clock
    currentSecs = "0" + currentSecs;
  }

  secs--;
  
  timer.textContent = currentMins + ":" + currentSecs;
  
  if (secs !== -1) {
    // Continue the countdown
    setTimeout(countdown, 1000);
  } else {
    // When countdown reaches 0...
    

    if (!comingOffBreak) {
      // If user just finished a pomodoro...
      countNumOfPomodoros();

      if (numOfPomodoros % 4 === 0) {
        button.textContent = "Start Long Break";
        resetForLongBreak();
      } else {
        button.textContent = "Start Short Break";
        resetForShortBreak();
      };
    } else {
      // If user just finished a break...
      button.textContent = "Start Pomodoro";
      resetCountdown();
    };
  };
}


function countNumOfPomodoros() {
  // Add 1 to numOfPomodoros after each pomodoro is completed
  numOfPomodoros++;
  return numOfPomodoros;
}

function resetCountdown() {
  // For new pomodoro
  mins = 25;
  secs = mins * 60;
  currentSecs = 0;
  currentMins = 0;
  comingOffBreak = false;
}

function resetForShortBreak() {
  mins = 5;
  secs = mins * 60;
  currentSecs = 0;
  currentMins = 0;
  comingOffBreak = true;
}

function resetForLongBreak() {
  mins = 30;
  secs = mins * 60;
  currentSecs = 0;
  currentMins = 0;
  comingOffBreak = true;
}

<div class="container text-center">
  <h1 id="title">POMODORO CLOCK</h1>
  <div id="timerBox">
    <span id="timer">25:00</span>
  </div>
  <br>
  <button id="minus" class="btn btn-danger">- Minute </button>
  <button id="button" class="btn btn-success">Start Pomodoro</button>
  <button id="add" class="btn btn-primary">+  Minute</button>
</div>

Answer 1

You are updating the mins variable in the method and the text, but not the seconds that are the variables considered in countdown method.

I would also consider to refactor it as the follows:

• have a variable with the start of a pomodoro cicle,
• have another variable with the number of mins increased,
• then use the following pseudo-expression to get the remaining seconds to be displayed, without updating with countdowns the variables: 25 * 60 + extraMins * 60 - <current-time-in-secs> + <start-time-in-secs>