Build a Custom Calendar App with D3 Data Visualization

Building a Google Calendar Clone with D3.js

Learning by Imitation

Recreating a popular application is an excellent way to gain hands-on experience with a new technology or enhance existing skills. In this case, we’ll use D3.js to build a Google Calendar clone, exploring the library’s capabilities in the process.

Setting Up the Project

To begin, create a new directory and set up a Snowpack project. Run the following command in your terminal:

npx snowpack init calendar-clone

Next, create an index.html file in the root directory with the following content:
“`html


Create an `index.js` file in the same directory and add a console log statement to ensure everything is running correctly:
javascript
console.log(‘Hello, world!’);
“`
Building the App

Clear out the previous test code and import D3.js. Declare a JSON object containing calendar events and a dates array:
“`javascript
import * as d3 from ‘d3-array’;

const calendarEvents = […]; // add your events here
const dates = […]; // add your dates here
“`
Designing the Visualization

Declare standard D3 variables, such as margin, height, and width, as well as specific variables for our calendar:
javascript
const margin = { top: 20, right: 20, bottom: 30, left: 40 };
const height = 500;
const width = 800;
const barWidth = 20;
const nowColor = 'ed';

Adding Scale Functions

Create scale functions to map data points to pixel values on our visualization:
javascript
const yScale = d3.scaleLinear()
.domain([0, 24])
.range([height - margin.top - margin.bottom, 0]);

Drawing the Y-Axis

Use the scale mapping to draw the y-axis:
javascript
const yAxis = d3.axisLeft(yScale)
.ticks(24)
.tickFormat(d3.format('02d'));

Customizing Tick Styling

Style the first and last ticks to display midnight (12AM):
javascript
yAxis.tickFormat((d, i) => {
if (i === 0 || i === 23) {
return '12AM';
}
return d3.format('02d')(d);
});

Adding Grid Lines

Create grid lines for design:
javascript
const xAxis = d3.axisRight(yScale)
.ticks(24);

Using the Calendar Events Array

Add calendar events using the join method:
javascript
const barGroups = svg.selectAll('g.barGroup')
.data(calendarEvents)
.join('g')
.attr('class', 'barGroup');

Appending Elements

Append rectangles for each calendar event:
javascript
barGroups.append('rect')
.attr('x', 0)
.attr('y', (d, i) => yScale(d.start))
.attr('width', barWidth)
.attr('height', (d, i) => yScale(d.end) - yScale(d.start));

Tracking Current Time

Add a line to track the current time:
javascript
svg.append('line')
.attr('x1', 0)
.attr('y1', yScale(new Date().getHours()))
.attr('x2', width)
.attr('y2', yScale(new Date().getHours()))
.attr('stroke', nowColor);

Labeling Events

Add labels for each event:
javascript
barGroups.append('text')
.attr('x', 0)
.attr('y', (d, i) => yScale(d.start))
.text(d => d.title);

Final Product

Congratulations! You’ve built a basic calendar app using D3.js. This is just the beginning – you can continue to improve and expand the app to include more features.

Monitoring Your App’s Performance

As you add new JavaScript libraries and dependencies to your app, ensure you have visibility into any issues that may arise. LogRocket is a frontend application monitoring solution that lets you replay JavaScript errors and monitor performance metrics like client CPU load and memory usage. Start monitoring for free today!