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







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

There are a lot of issues when constructing a calendar element — way over what is roofed within the articles I linked up. If you concentrate on it, calendars are fraught with nuance, from dealing with timezones and date codecs to localization and even ensuring dates move from one month to the following… 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 numerous cool APIs and stuff to assist out!

January 2023 calendar grid.

I don’t wish 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 among the nuances you may not usually see. And, within the course of, I hope you’ll acquire a brand new appreciation for newer issues that JavaScript can do whereas getting an thought of the types of issues that cross my thoughts after I’m placing one thing like this collectively.

First off, naming

What ought to we name our calendar element? In my native language, it will be known as “kalender component”, 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 methodology will render a single month. Later we’ll name this methodology from [...Array(12).keys()] to render a complete yr.

Preliminary information and internationalization

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

const at present = new Date();

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

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

We verify, if the basis component (<html>) comprises a lang-attribute with locale information; 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 manner, if no date is supplied within the settings object, we’ll use the at present reference as a substitute:

const date = ? new Date( : at present;

We want a little bit extra information to correctly format the calendar primarily based on locale. For instance, we would not know whether or not the primary day of the week is Sunday or Monday, relying on the locale. If we have now the information, 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 in search of with none problem. We are able to additionally get which days of the week are assigned to the weekend:

if (!config.information) config.information = 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 worth of 7. This can be a little complicated, because the getDay methodology 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 methodology, it was fairly arduous 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 tactic 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 in the future. For others, it is likely to be a full seven days.

Subsequent, we’ll create a render methodology 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 === present.yr) && (month === present.month);

The final one is a Boolean that checks whether or not at present 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 wish to ensure that the main points 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 have now the non-semantic wrapper: <kal-el>. That’s wonderful as a result of there isn’t a semantic <calendar> tag or something like that. If we weren’t making a customized component, <article> is likely to be essentially the most applicable component for the reason that calendar might stand by itself web page.

Month names

The <time> component goes to be a giant one for us as a result of it helps translate dates right into a format that screenreaders and serps can parse extra precisely and constantly. 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 many others. — however that may take up numerous area. 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 many others. -->

We might get tough with CSS to get one of the 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 are able to then “cover” the total title when area runs out and show the title attribute as a substitute:

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

However, we’re not going that method as a result of the Intl.DateTimeFormat API might help right here as effectively. We’ll get to that within the subsequent part once 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 record (<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 option to fashion the date numbers. That’s attainable as-is, however I additionally need to have the ability to fashion weekday numbers in a different 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 widespread, it may be good to show the quantity for a given week within the calendar for added 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 embrace 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 component. 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="${ config.information.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 wish to use the lengthy title (e.g. February) or the quick 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 quick (abbreviated, ie. “Solar”) names. This manner, we will use the “quick” title when the calendar is brief on area:

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

Let’s make a small helper methodology that makes it a little bit 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),
      quick: new Intl.DateTimeFormat([locale], { weekday: 'quick'}).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:

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

Day numbers

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

${[...Array(numOfDays).keys()].map(i => {
  const cur = new Date(yr, month, i + 1);
  let day = cur.getDay(); if (day === 0) day = 7;
  const at present = renderToday && ( === i + 1) ? ' data-today':'';
  return `
    <li data-day="${day}"${at present}${i === 0 || day === config.information.firstDay ? ` data-weeknumber="${new Intl.NumberFormat(locale).format(getWeek(cur))}"`:''}${config.information.weekend.contains(day) ? ` data-weekend`:''}>
      <time datetime="${yr}-${(pad(month))}-${pad(i)}" tabindex="0">
        ${new Intl.NumberFormat(locale).format(i + 1)}
}).be a 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 at present, we add a data-* attribute.
  5. Lastly, we return the <li> component as a string with merged information.
  6. tabindex="0" makes the component focusable, when utilizing keyboard navigation, after any optimistic tabindex values (Observe: you must by no means add optimistic tabindex-values)

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

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

Week quantity

Once more, the “week quantity” is the place per week falls in a 52-week calendar. We use a little bit helper methodology for that as effectively:

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! Because of the Intl.Locale, Intl.DateTimeFormat and Intl.NumberFormat APIs, we will now merely change the lang-attribute of the <html> component to vary 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 record gadgets. To fashion these right into a readable calendar, we dive into the fantastic world of CSS Grid. The truth is, 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 wonderful when the primary day of the month is additionally the primary day of the week for the chosen locale). However that’s the exception fairly 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.

Bear in mind all the additional data-* attributes we outlined when writing our markup? We are able to 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 can mechanically “push” the following merchandise (Day 2) to the fifth grid column, and so forth.

Let’s add a little bit fashion to the “present” date, so it stands out. These are simply my types. You may 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 a different way than weekdays. I’m going to make use of a reddish colour to fashion these. Observe that we will attain for the :not() pseudo-class to pick 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 overlook 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 until 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 carried out at this level! We are able to render a calendar grid that reveals the dates for the present month, full with issues for localizing the information by locale, and making certain that the calendar makes use of correct semantics. And all we used was vanilla JavaScript and CSS!

However let’s take this yet one more step

Rendering a complete yr

Possibly it’s essential show a full yr of dates! So, fairly than render the present month, you may wish 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 methodology 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 a part of('')

It’s in all probability a good suggestion to create a brand new guardian wrapper for the rendered yr. Every calendar grid is a <kal-el> component. Let’s name the brand new guardian 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 many others. -->

  <!-- different months -->

We are able to 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);

Closing demo

Bonus: Confetti Calendar

I learn a wonderful guide known as Making and Breaking the Grid the opposite day and came across this stunning “New 12 months’s poster”:

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

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


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