Making Calendars With Accessibility and Internationalization in Thoughts | CSS-Methods


Doing a fast search right here on CSS-Methods reveals simply what number of other ways there are to strategy calendars. Some present how CSS Grid can create the format effectively. Some try to carry precise information into the combo. Some depend on a framework to assist with state administration.

There are a lot of issues when constructing a calendar part — way over what is roofed within the articles I linked up. If you consider it, calendars are fraught with nuance, from dealing with timezones and date codecs to localization and even ensuring dates circulation from one month to the subsequent… and that’s earlier than we even get into accessibility and extra format issues relying on the place the calendar is displayed and whatnot.

Many builders concern the Date() object and persist with older libraries like second.js. However whereas there are various “gotchas” in relation to dates and formatting, JavaScript has quite a lot of cool APIs and stuff to assist out!

January 2023 calendar grid.

I don’t need to re-create the wheel right here, however I’ll present you the way we will get a dang good calendar with vanilla JavaScript. We’ll look into accessibility, utilizing semantic markup and screenreader-friendly <time> -tags — in addition to internationalization and formatting, utilizing the Intl.Locale, Intl.DateTimeFormat and Intl.NumberFormat-APIs.

In different phrases, we’re making a calendar… solely with out the additional dependencies you may usually see utilized in a tutorial like this, and with a few of the nuances you may not usually see. And, within the course of, I hope you’ll achieve a brand new appreciation for newer issues that JavaScript can do whereas getting an concept of the kinds of issues that cross my thoughts once I’m placing one thing like this collectively.

First off, naming

What ought to we name our calendar part? In my native language, it might be referred to as “kalender ingredient”, so let’s use that and shorten that to “Kal-El” — also referred to as Superman’s title on the planet Krypton.

Let’s create a operate to get issues going:

operate kalEl(settings = {}) { ... }

This technique will render a single month. Later we’ll name this technique from [...Array(12).keys()] to render a whole yr.

Preliminary information and internationalization

One of many frequent issues a typical on-line calendar does is spotlight the present date. So let’s create a reference for that:

const immediately = new Date();

Subsequent, we’ll create a “configuration object” that we’ll merge with the elective settings object of the first technique:

const config = Object.assign(
    locale: (doc.documentElement.getAttribute('lang') || 'en-US'), 
    immediately: { 
      day: immediately.getDate(),
      month: immediately.getMonth(),
      yr: immediately.getFullYear() 
  }, settings

We test, if the basis ingredient (<html>) incorporates a lang-attribute with locale data; in any other case, we’ll fallback to utilizing en-US. This is step one towards internationalizing the calendar.

We additionally want to find out which month to initially show when the calendar is rendered. That’s why we prolonged the config object with the first date. This fashion, if no date is supplied within the settings object, we’ll use the immediately reference as an alternative:

const date = ? new Date( : immediately;

We’d like just a little extra data to correctly format the calendar primarily based on locale. For instance, we’d not know whether or not the primary day of the week is Sunday or Monday, relying on the locale. If we’ve the data, nice! But when not, we’ll replace it utilizing the Intl.Locale API. The API has a weekInfo object that returns a firstDay property that provides us precisely what we’re on the lookout for with none trouble. We will additionally get which days of the week are assigned to the weekend:

if (! = new Intl.Locale(config.locale).weekInfo || { 
  firstDay: 7,
  weekend: [6, 7] 

Once more, we create fallbacks. The “first day” of the week for en-US is Sunday, so it defaults to a price of 7. It is a little complicated, because the getDay technique in JavaScript returns the times as [0-6], the place 0 is Sunday… don’t ask me why. The weekends are Saturday and Sunday, therefore [6, 7].

Earlier than we had the Intl.Locale API and its weekInfo technique, it was fairly exhausting to create a global calendar with out many **objects and arrays with details about every locale or area. These days, it’s easy-peasy. If we go in en-GB, the strategy returns:

// en-GB
  firstDay: 1,
  weekend: [6, 7],
  minimalDays: 4

In a rustic like Brunei (ms-BN), the weekend is Friday and Sunday:

// ms-BN
  firstDay: 7,
  weekend: [5, 7],
  minimalDays: 1

You may surprise what that minimalDays property is. That’s the fewest days required within the first week of a month to be counted as a full week. In some areas, it is likely to be simply at some point. For others, it is likely to be a full seven days.

Subsequent, we’ll create a render technique inside our kalEl-method:

const render = (date, locale) => { ... }

We nonetheless want some extra information to work with earlier than we render something:

const month = date.getMonth();
const yr = date.getFullYear();
const numOfDays = new Date(yr, month + 1, 0).getDate();
const renderToday = (yr === config.immediately.yr) && (month === config.immediately.month);

The final one is a Boolean that checks whether or not immediately exists within the month we’re about to render.

Semantic markup

We’re going to get deeper in rendering in only a second. However first, I need to be sure that the small print we arrange have semantic HTML tags related to them. Setting that up proper out of the field provides us accessibility advantages from the beginning.

Calendar wrapper

First, we’ve the non-semantic wrapper: <kal-el>. That’s effective as a result of there isn’t a semantic <calendar> tag or something like that. If we weren’t making a customized ingredient, <article> is likely to be essentially the most acceptable ingredient for the reason that calendar may stand by itself web page.

Month names

The <time> ingredient goes to be a giant one for us as a result of it helps translate dates right into a format that screenreaders and search engines like google can parse extra precisely and persistently. For instance, right here’s how we will convey “January 2023” in our markup:

<time datetime="2023-01">January <i>2023</i></time>

Day names

The row above the calendar’s dates containing the names of the times of the week may be tough. It’s perfect if we will write out the total names for every day — e.g. Sunday, Monday, Tuesday, and so forth. — however that may take up quite a lot of house. So, let’s abbreviate the names for now inside an <ol> the place every day is a <li>:

  <li><abbr title="Sunday">Solar</abbr></li>
  <li><abbr title="Monday">Mon</abbr></li>
  <!-- and so forth. -->

We may get tough with CSS to get the very best of each worlds. For instance, if we modified the markup a bit like this:

    <abbr title="S">Sunday</abbr>

…we get the total names by default. We will then “disguise” the total title when house runs out and show the title attribute as an alternative:

@media all and (max-width: 800px) {
  li abbr::after {
    content material: attr(title);

However, we’re not going that means as a result of the Intl.DateTimeFormat API might help right here as nicely. We’ll get to that within the subsequent part after we cowl rendering.

Day numbers

Every date within the calendar grid will get a quantity. Every quantity is an inventory merchandise (<li>) in an ordered listing (<ol>), and the inline <time> tag wraps the precise quantity.

  <time datetime="2023-01-01">1</time>

And whereas I’m not planning on doing any styling simply but, I do know I’ll need some method to model the date numbers. That’s attainable as-is, however I additionally need to have the ability to model weekday numbers in another way than weekend numbers if I must. So, I’m going to incorporate data-* attributes particularly for that: data-weekend and data-today.

Week numbers

There are 52 weeks in a yr, typically 53. Whereas it’s not tremendous frequent, it may be good to show the quantity for a given week within the calendar for extra context. I like having it now, even when I don’t wind up not utilizing it. However we’ll completely use it on this tutorial.

We’ll use a data-weeknumber attribute as a styling hook and embody it within the markup for every date that’s the week’s first date.

<li data-day="7" data-weeknumber="1" data-weekend="">
  <time datetime="2023-01-08">8</time>


Let’s get the calendar on a web page! We already know that <kal-el> is the title of our customized ingredient. Very first thing we have to configure it’s to set the firstDay property on it, so the calendar is aware of whether or not Sunday or another day is the primary day of the week.

<kal-el data-firstday="${ }">

We’ll be utilizing template literals to render the markup. To format the dates for a global viewers, we’ll use the Intl.DateTimeFormat API, once more utilizing the locale we specified earlier.

The month and yr

After we name the month, we will set whether or not we need to use the lengthy title (e.g. February) or the brief title (e.g. Feb.). Let’s use the lengthy title because it’s the title above the calendar:

<time datetime="${yr}-${(pad(month))}">
  ${new Intl.DateTimeFormat(
    { month:'lengthy'}).format(date)} <i>${yr}</i>

Weekday names

For weekdays displayed above the grid of dates, we want each the lengthy (e.g. “Sunday”) and brief (abbreviated, ie. “Solar”) names. This fashion, we will use the “brief” title when the calendar is brief on house:

Intl.DateTimeFormat([locale], { weekday: 'lengthy' })
Intl.DateTimeFormat([locale], { weekday: 'brief' })

Let’s make a small helper technique that makes it just a little simpler to name each:

const weekdays = (firstDay, locale) => {
  const date = new Date(0);
  const arr = [...Array(7).keys()].map(i => {
    date.setDate(5 + i)
    return {
      lengthy: new Intl.DateTimeFormat([locale], { weekday: 'lengthy'}).format(date),
      brief: new Intl.DateTimeFormat([locale], { weekday: 'brief'}).format(date)
  for (let i = 0; i < 8 - firstDay; i++) arr.splice(0, 0, arr.pop());
  return arr;

Right here’s how we invoke that within the template:

  ${weekdays(,locale).map(title => `
      <abbr title="${title.lengthy}">${title.brief}</abbr>
    </li>`).be part of('')

Day numbers

And eventually, the times, wrapped in an <ol> ingredient:

${[...Array(numOfDays).keys()].map(i => {
  const cur = new Date(yr, month, i + 1);
  let day = cur.getDay(); if (day === 0) day = 7;
  const immediately = renderToday && ( === i + 1) ? ' data-today':'';
  return `
    <li data-day="${day}"${immediately}${i === 0 || day === ? ` data-weeknumber="${new Intl.NumberFormat(locale).format(getWeek(cur))}"`:''}${ ? ` data-weekend`:''}>
      <time datetime="${yr}-${(pad(month))}-${pad(i)}" tabindex="0">
        ${new Intl.NumberFormat(locale).format(i + 1)}
}).be part of('')}

Let’s break that down:

  1. We create a “dummy” array, primarily based on the “variety of days” variable, which we’ll use to iterate.
  2. We create a day variable for the present day within the iteration.
  3. We repair the discrepancy between the Intl.Locale API and getDay().
  4. If the day is the same as immediately, we add a data-* attribute.
  5. Lastly, we return the <li> ingredient as a string with merged information.
  6. tabindex="0" makes the ingredient focusable, when utilizing keyboard navigation, after any optimistic tabindex values (Be aware: it is best to by no means add optimistic tabindex-values)

To “pad” the numbers within the datetime attribute, we use just a little helper technique:

const pad = (val) => (val + 1).toString().padStart(2, '0');

Week quantity

Once more, the “week quantity” is the place every week falls in a 52-week calendar. We use just a little helper technique for that as nicely:

operate getWeek(cur) {
  const date = new Date(cur.getTime());
  date.setHours(0, 0, 0, 0);
  date.setDate(date.getDate() + 3 - (date.getDay() + 6) % 7);
  const week = new Date(date.getFullYear(), 0, 4);
  return 1 + Math.spherical(((date.getTime() - week.getTime()) / 86400000 - 3 + (week.getDay() + 6) % 7) / 7);

I didn’t write this getWeek-method. It’s a cleaned up model of this script.

And that’s it! Due to the Intl.Locale, Intl.DateTimeFormat and Intl.NumberFormat APIs, we will now merely change the lang-attribute of the <html> ingredient to alter the context of the calendar primarily based on the present area:

January 2023 calendar grid.
January 2023 calendar grid.
January 2023 calendar grid.

Styling the calendar

You may recall how all the times are only one <ol> with listing gadgets. To model these right into a readable calendar, we dive into the great world of CSS Grid. In actual fact, we will repurpose the identical grid from a starter calendar template proper right here on CSS-Methods, however up to date a smidge with the :is() relational pseudo to optimize the code.

Discover that I’m defining configurable CSS variables alongside the best way (and prefixing them with ---kalel- to keep away from conflicts).

kal-el :is(ol, ul) {
  show: grid;
  font-size: var(--kalel-fz, small);
  grid-row-gap: var(--kalel-row-gap, .33em);
  grid-template-columns: var(--kalel-gtc, repeat(7, 1fr));
  list-style: none;
  margin: unset;
  padding: unset;
  place: relative;
Seven-column calendar grid with grid lines shown.

Let’s draw borders across the date numbers to assist separate them visually:

kal-el :is(ol, ul) li {
  border-color: var(--kalel-li-bdc, hsl(0, 0%, 80%));
  border-style: var(--kalel-li-bds, stable);
  border-width: var(--kalel-li-bdw, 0 0 1px 0);
  grid-column: var(--kalel-li-gc, preliminary);
  text-align: var(--kalel-li-tal, finish); 

The seven-column grid works effective when the primary day of the month is additionally the primary day of the week for the chosen locale). However that’s the exception moderately than the rule. Most instances, we’ll must shift the primary day of the month to a special weekday.

Showing the first day of the month falling on a Thursday.

Keep in mind all the additional data-* attributes we outlined when writing our markup? We will hook into these to replace which grid column (--kalel-li-gc) the primary date variety of the month is positioned on:

[data-firstday="1"] [data-day="3"]:first-child {
  --kalel-li-gc: 1 / 4;

On this case, we’re spanning from the primary grid column to the fourth grid column — which is able to routinely “push” the subsequent merchandise (Day 2) to the fifth grid column, and so forth.

Let’s add just a little model to the “present” date, so it stands out. These are simply my types. You possibly can completely do what you’d like right here.

[data-today] {
  --kalel-day-bdrs: 50%;
  --kalel-day-bg: hsl(0, 86%, 40%);
  --kalel-day-hover-bgc: hsl(0, 86%, 70%);
  --kalel-day-c: #fff;

I like the thought of styling the date numbers for weekends in another way than weekdays. I’m going to make use of a reddish shade to model these. Be aware that we will attain for the :not() pseudo-class to pick out them whereas leaving the present date alone:

[data-weekend]:not([data-today]) { 
  --kalel-day-c: var(--kalel-weekend-c, hsl(0, 86%, 46%));

Oh, and let’s not neglect the week numbers that go earlier than the primary date variety of every week. We used a data-weeknumber attribute within the markup for that, however the numbers gained’t truly show except we reveal them with CSS, which we will do on the ::earlier than pseudo-element:

[data-weeknumber]::earlier than {
  show: var(--kalel-weeknumber-d, inline-block);
  content material: attr(data-weeknumber);
  place: absolute;
  inset-inline-start: 0;
  /* extra types */

We’re technically achieved at this level! We will render a calendar grid that reveals the dates for the present month, full with issues for localizing the information by locale, and guaranteeing that the calendar makes use of correct semantics. And all we used was vanilla JavaScript and CSS!

However let’s take this another step

Rendering a whole yr

Perhaps you have to show a full yr of dates! So, moderately than render the present month, you may need to show all the month grids for the present yr.

Nicely, the good factor in regards to the strategy we’re utilizing is that we will name the render technique as many instances as we would like and merely change the integer that identifies the month on every occasion. Let’s name it 12 instances primarily based on the present yr.

so simple as calling the render-method 12 instances, and simply change the integer for monthi:

[...Array(12).keys()].map(i =>
    new Date(date.getFullYear(),
).be part of('')

It’s most likely a good suggestion to create a brand new mum or dad wrapper for the rendered yr. Every calendar grid is a <kal-el> ingredient. Let’s name the brand new mum or dad wrapper <jor-el>, the place Jor-El is the title of Kal-El’s father.

<jor-el id="app" data-year="true">
  <kal-el data-firstday="7">
    <!-- and so forth. -->

  <!-- different months -->

We will use <jor-el> to create a grid for our grids. So meta!

jor-el {
  background: var(--jorel-bg, none);
  show: var(--jorel-d, grid);
  hole: var(--jorel-gap, 2.5rem);
  grid-template-columns: var(--jorel-gtc, repeat(auto-fill, minmax(320px, 1fr)));
  padding: var(--jorel-p, 0);

Remaining demo

Bonus: Confetti Calendar

I learn a wonderful ebook referred to as Making and Breaking the Grid the opposite day and found this stunning “New Yr’s poster”:

Supply: Making and Breaking the Grid (2nd Version) by Timothy Samara

I figured we may do one thing related with out altering something within the HTML or JavaScript. I’ve taken the freedom to incorporate full names for months, and numbers as an alternative of day names, to make it extra readable. Take pleasure in!


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