Build a Pomodoro Timer using HTML, CSS and Javascript
Tags: javascript, webdev, tutorial, css
Published: 2021-12-21 13:45:22

In this tutorial, we are coding a Pomodoro timer. ⏲

I Came across Advent Of CSS and Advent of JS challenges, created by Amy Dutton and James Q Quick for this holiday season.  I decided it would be a fun little challenge to participate this year!

So here is my learning and challenges faced during the Day 1 challenge. 😥

## What is a Pomodoro Timer?

> The Pomodoro Technique is a time management method developed by Francesco Cirillo in the late 1980s. It uses a timer to break work into intervals, traditionally 25 minutes in length, separated by short breaks. Each interval is known as a Pomodoro, from the Italian word for tomato, after the tomato-shaped kitchen timer Cirillo used as a university student.  -- Wikipedia


![What is Pomodoro](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/j39rssiyfzaisrirfcwa.png)

In simple words, a Pomodoro timer is a simple app that helps us to focus and be productive. It schedules alternate work and breaks sessions.

## Challenge Spec

Users should be able to:

- Start the timer by clicking on the 'START' link/button.
- Once the user clicks start, the word start will change to STOP. Then, the user can click on the 'STOP' button to make the timer stop.
- Click on the Gear icon to change the length (minutes and seconds) of the timer.
- Once the timer finishes, the ring should change from red to green.
- Can use any frameworks, libraries, tools or can stay with good old CSS and Vanilla JS.


![Design Specification](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/ncuxwzsvfnbhftgjjzme.gif)
I decided to stay with my old friends, **plain CSS and Vanilla JS** 🤞🏻

*So, it's time for some code!*

## Approach: HTML

We will start by creating a simple HTML structure to display a timer and Start/Stop and a Setting's Button(to adjust the time)
```
<div class="container">
	<div class="outerRing">
		<div class="timer">
			<!-- Timer elements -->
		</div>
	</div>
</div>
```
A `container` contains everything for the timer. 

Inside the `container`, we have two `div`'s.

One for `outerRing` displaying the progress bar.

Second for the `timer` to display the *Countdown, Start/Stop and the Settings button*.

```
<div id="time">
	<span id="minutes">00</span>
	<span id="colon">:</span>
	<span id="seconds">10</span>
</div>
<div id="stsp">START</div>
<span id="setting"><i class="fas fa-cog"></i></span>
```
The `time` div displays the countdown, with `minutes` and `seconds` `<span>`.

Below is the complete HTML code.
```
<div class="container">
	<div class="outerRing">
		<div class="timer">
			<div id="time">
				<span id="minutes">00</span>
				<span id="colon">:</span>
				<span id="seconds">10</span>
			</div>
			<div id="stsp">START</div>
			<span id="setting"><i class="fas fa-cog"></i></span>
		</div>
	</div>
</div>
```

## Approach: Adding CSS

First, set the `: root` variables. Then add the `container` layout to the centre of the page using `display: grid`.

Set the outer ring and the timer to circle with a difference of `15px` between `outerRing` and `timer` containers.
```
.outerRing {
	display: grid;
	place-items: center;
	width: 415px;
	height: 415px;
	border-radius: 50%;
	box-shadow: -5px 14px 44px #000000, 
      5px -16px 50px rgba(255, 255, 255, 0.15);
	background: var(--normal-ring);
}

/* Width and Height difference btwn .outerRing & .timer is 15px, 
where our progress bar will be displayed */

.timer {
	width: 400px;
	height: 400px;
	border-radius: 50%;
	background: var(--timer-bg);
	box-shadow: inset 0px 0px 114px rgba(0, 0, 0, 0.45);
	display: flex;
	justify-content: center;
	align-items: center;
	flex-direction: column;
	padding: 8rem;
}
```

`outerRing` is where we will be displaying the progress bar using the `conic-gradient()` function.

How Conic Gradient Works using animation 👇🏻👇🏻

[Codepen Link](https://codepen.io/skay/full/OJxRxjE)

We will be animating the progress bar using `conic-gradient()` colours in Javascript.

Below is the Complete CSS Code.
```
@import url("https://fonts.googleapis.com/css2?
family=Bebas+Neue&family=Montserrat:wght@700&display=swap");

*,
*::before,
*::after {
	margin: 0;
	padding: 0;
	box-sizing: border-box;
}

:root {
	--bg: #2b2a30;
	--normal-ring: #17171a;
	--red-ring: #9d0000;
	--green-ring: #00aa51;
	--timer-bg: radial-gradient(
		71.4% 71.4% at 51.7% 28.6%,
		#3a393f 0%,
		#17171a 100%
	);
	--font-timer: "Bebas Neue", cursive;
	--font-stsp: "Montserrat", sans-serif;
	--font-clr: #ffffff;
}

body {
	background: var(--bg);
	min-height: 100vh;
	overflow: hidden;
}

.container {
	height: 600px;
	width: 600px;
	background-color: transparent;
	position: absolute;
	transform: translate(-50%, -50%);
	top: 50%;
	left: 50%;
	display: grid;
	place-items: center;
}

.outerRing {
	display: grid;
	place-items: center;
	width: 415px;
	height: 415px;
	border-radius: 50%;
	box-shadow: -5px 14px 44px #000000, 
		5px -16px 50px rgba(255, 255, 255, 0.15);
	background: var(--normal-ring);
}

.timer {
	width: 400px;
	height: 400px;
	border-radius: 50%;
	background: var(--timer-bg);
	box-shadow: inset 0px 0px 114px rgba(0, 0, 0, 0.45);
	display: flex;
	justify-content: center;
	align-items: center;
	flex-direction: column;
	padding: 8rem;
}

#time {
	width: 300px;
	text-align: center;
	margin: 3rem 0 0 0;
}

#time span {
	display: inline;
	color: var(--font-clr);
	font-family: var(--font-timer);
	font-size: 7rem;
	letter-spacing: 0.1em;
	text-shadow: 0px 4px 4px rgba(0, 0, 0, 0.25);
}

#stsp {
	color: var(--font-clr);
	cursor: pointer;
	font-family: Montserrat;
	font-weight: bold;
	font-size: 1rem;
	line-height: 1.25rem;
	text-align: center;
	letter-spacing: 0.6em;
	margin: 1rem 0;
	text-shadow: 0px 4px 4px rgba(0, 0, 0, 0.25);
}

#setting {
	cursor: pointer;
	margin-top: 1rem;
	width: 25px;
	height: 25px;
	color: #585858;
	box-shadow: 0px 0px 2px rgba(0, 0, 0, 0.25);
}
```

## Approach: Adding Javascript

First, let us complete the timer ingredients like timer display, start/stop button & settings button.
- **Settings Button**

Get the `Setting`, `Minutes` and `Seconds` elements. Also, declare a `toggleSettings` variable to keep track of the click of the `Settings` button.
```
const minElem = document.querySelector("#minutes"),
	secElem = document.querySelector("#seconds"),
	setting = document.querySelector("#setting");

let toggleSettings = false;
```
Handle the `click` event on the `Settings` button. Also, handle the `onblur` event for the `Minutes` and `Seconds` elements.
```
setting.onclick = function () {
	if (!toggleSettings) {
		toggleSettings = true;
		minElem.contentEditable = true;
		minElem.style.borderBottom = `1px dashed #ffffff50`;
		secElem.contentEditable = true;
		secElem.style.borderBottom = `1px dashed #ffffff50`;
	} else {
		resetValues();
	}
};

minElem.onblur = function () {
	resetValues();
};

secElem.onblur = function () {
	resetValues();
};

```
The function `resetValues` handles the values getting reassigned for `minutes` and `seconds`.

- **Start/Stop Button**

Declare `minutes` and `seconds` as `let` variables, as we will manipulate these for the timer display.
```
const startStop = document.querySelector("#stsp");
let minutes = document.querySelector("#minutes").innerHTML,
	seconds = document.querySelector("#seconds").innerHTML;
```
When we click the `START` button, first will check for `minutes` and `seconds` not equal to 0. Then the text will change to `STOP` and call the `startStopProgress` function. 

The `startStopProgress` function will check the timer progress and update the progress bar and the timer display. 

If the `STOP` button, use the same function to clear the progress and change the text back to `START`.
```
startStop.onclick = function () {
	if (startStop.innerHTML === "START") {
		if (!(parseInt(minutes) === 0 && parseInt(seconds) === 0)) {
			startStop.innerHTML = "STOP";
			startStopProgress();
		} else {
			alert("Enter the Time Value in your Timer!");
		}
	} else {
		startStop.innerHTML = "START";
		startStopProgress();
	}
};
```
- **Progress Bar**

We will be using `setInterval()` to run our code that helps track the progress.

```
function startStopProgress() {
	if (!progress) {
		progress = setInterval(progressTrack, speed);
	} else {
		clearInterval(progress);
		progress = null;
		progressStart = 0;
		progressBar.style.background = `conic-gradient(
				#17171a 360deg,
				#17171a 360deg
		  )`;
	}
}
```
Calculate the Minutes Remaining and Seconds Remaining to update the timer. 

Also, depending on the total time of the timer, calculate the degree/second on the timer. 
```
Degree/Second = 360 / Total time of the timer in minutes.
```

Using `conic-gradient()` and the calculated deg/sec, update the DOM.

```
function progressTrack() {
	progressStart++;

	secRem = Math.floor((progressEnd - progressStart) % 60);
	minRem = Math.floor((progressEnd - progressStart) / 60);

	secElem.innerHTML = secRem.toString().length == 2 ? secRem : `0${secRem}`;
	minElem.innerHTML = minRem.toString().length == 2 ? minRem : `0${minRem}`;

	progressBar.style.background = `conic-gradient(
      	#9d0000 ${progressStart * degTravel}deg,
      	#17171a ${progressStart * degTravel}deg
  		)`;
	if (progressStart == progressEnd) {
		progressBar.style.background = `conic-gradient(
				#00aa51 360deg,
				#00aa51 360deg
		  )`;
		clearInterval(progress);
		startStop.innerHTML = "START";
		progress = null;
		progressStart = 0;
	}
}
```
Here is the complete Javascript code,
```
const progressBar = document.querySelector(".outerRing"),
	minElem = document.querySelector("#minutes"),
	secElem = document.querySelector("#seconds"),
	startStop = document.querySelector("#stsp"),
	setting = document.querySelector("#setting");

let minutes = document.querySelector("#minutes").innerHTML,
	seconds = document.querySelector("#seconds").innerHTML,
	progress = null,
	progressStart = 0,
	progressEnd = parseInt(minutes) * 60 + parseInt(seconds),
	speed = 1000,
	degTravel = 360 / progressEnd,
	toggleSettings = false,
	secRem = 0,
	minRem = 0;

function progressTrack() {
	progressStart++;

	secRem = Math.floor((progressEnd - progressStart) % 60);
	minRem = Math.floor((progressEnd - progressStart) / 60);

	secElem.innerHTML = secRem.toString().length == 2 ? secRem : `0${secRem}`;
	minElem.innerHTML = minRem.toString().length == 2 ? minRem : `0${minRem}`;

	progressBar.style.background = `conic-gradient(
      	#9d0000 ${progressStart * degTravel}deg,
      	#17171a ${progressStart * degTravel}deg
  		)`;
	if (progressStart == progressEnd) {
		progressBar.style.background = `conic-gradient(
				#00aa51 360deg,
				#00aa51 360deg
		  )`;
		clearInterval(progress);
		startStop.innerHTML = "START";
		progress = null;
		progressStart = 0;
	}
}

function startStopProgress() {
	if (!progress) {
		progress = setInterval(progressTrack, speed);
	} else {
		clearInterval(progress);
		progress = null;
		progressStart = 0;
		progressBar.style.background = `conic-gradient(
				#17171a 360deg,
				#17171a 360deg
		  )`;
	}
}

function resetValues() {
	if (progress) {
		clearInterval(progress);
	}
	minutes = document.querySelector("#minutes").innerHTML;
	seconds = document.querySelector("#seconds").innerHTML;
	toggleSettings = false;
	minElem.contentEditable = false;
	minElem.style.borderBottom = `none`;
	secElem.contentEditable = false;
	secElem.style.borderBottom = `none`;
	progress = null;
	progressStart = 0;
	progressEnd = parseInt(minutes) * 60 + parseInt(seconds);
	degTravel = 360 / progressEnd;
	progressBar.style.background = `conic-gradient(
				#17171a 360deg,
				#17171a 360deg
		  )`;
}

startStop.onclick = function () {
	if (startStop.innerHTML === "START") {
		if (!(parseInt(minutes) === 0 && parseInt(seconds) === 0)) {
			startStop.innerHTML = "STOP";
			startStopProgress();
		} else {
			alert("Enter the Time Value in your Timer!");
		}
	} else {
		startStop.innerHTML = "START";
		startStopProgress();
	}
};

setting.onclick = function () {
	if (!toggleSettings) {
		toggleSettings = true;
		minElem.contentEditable = true;
		minElem.style.borderBottom = `1px dashed #ffffff50`;
		secElem.contentEditable = true;
		secElem.style.borderBottom = `1px dashed #ffffff50`;
	} else {
		resetValues();
	}
};

minElem.onblur = function () {
	resetValues();
};

secElem.onblur = function () {
	resetValues();
};
```
Wow, that's it!  🤩🤩

## Conclusion!

We have successfully created the Pomodoro timer using HTML, CSS and Javascript. 

We can extend this to add more functionalities like the 'PAUSE' button etc.,

If you have any issues, please refer to the full codepen below,

[Codepen Link](https://codepen.io/skay/pen/xxXGKZy)

For more articles like this, visit [The Introvert Coder](https://theintrovertcoder.hashnode.dev/) and Follow me on [Twitter](https://twitter.com/sangyk_dev).

Thanks for reading, and happy coding!