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25 + 5 Clock

FreeCodeCamp.org - Front End Development Libraries Project

This is a solution to the Build a 25 + 5 Clock project.

Table of contents


The challenge

Users should be able to:

  • Click the element with id="reset", any running timer should be stopped, the break timer should return to 5, the session timer should return to 25, and the time should reset to its default state.
  • Click the element with id="start_stop", the timer should begin running from the value currently displayed, even if the value has been incremented or decremented from the original value of 25.
  • If the timer is paused and they click the element with id="start_stop", the countdown should resume running from the point at which it was paused.
  • The timer should switch between break and session timers when the clock hits zero.
  • There is a sound played when the timer countdown switches.

Additional things I did:

  • The timers are designed to resemble playing cards. They are all tilted slightly.
  • The countdown timer (middle card) tilts towards the currently active time (to the left by default). It tilts to the right when the break timer is active.
  • There are two different sound effects playing when the timer switches over, depending on which timer is currently active.
  • There is also an image that appears on the middle card while switching over.

My process

Built with

  • Semantic HTML
  • React.js
  • Scss

What I learned

Figuring out accurate timing is hard!

The order of the functions and methods called matter very much to the time based tests in this one.

Also, there is more than one way to make a countdown timer.

const doIntervalChange = () => {
  let minutes = Math.floor(totalTime / 60);
  let seconds = totalTime % 60;
  seconds = seconds < 10 ? "0" + seconds : seconds; //Formatting the seconds and minutes
  minutes = minutes < 10 ? "0" + minutes : minutes;
  timerMinutes.current = minutes;
  timerSeconds.current = seconds;
  setTotalTime(totalTime - 1);

UseEffect is pretty USEful! (Get it?)

useEffect(() => {
  let interval = setInterval(() => {
    if (timerMinutes.current === "00") {
      alert.current = true;
    } else {
      alert.current = false;
    if (!countingDown) {
      return; // If the timer is not active, do nothing
    if (totalTime <= 0) {
      playAudio(); // Play Audio when time is up
    if (countingDown && totalTime >= 0) {
      //Countdown only until zero
    } else {
      switching.current = true;
      props.switchOver(); //Switchover to the other timer
      refresh(); // update the timer again
      setInterval(() => {
        switching.current = false;
      }, 4500);
  }, 1000); // 1 second intervals
  return () => clearInterval(interval);

Continued development

The timer is probably not as accurate as I want it to be.

Some transitions are late by a few seconds or stop abruptly.

I also don't think this is the most efficient code ever, it probably needs a lot of optimization.

Useful resources



Thanks to Ms. Jessica Chan (Coder Coder) and all the other YouTube creators making their knowledge available!

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