This SVG will always show todays date

Language:: JavaScript, HTML
Program::
Link:: GitHub - edent/Dynamic-SVG-Calendar-Icon: Here it is, an SVG calendar which always display's today's date.

Summary

This SVG will always show todays date

Code

edent/Dynamic-SVG-Calendar-Icon

Originally posted on my blog.

For my contact page, I wanted a generic calendar icon to let people view my diary. Calendar icons are almost always a skeuomorph of a paper calendar, but I wondered if I could make it slightly more useful by creating a dynamic icon.

Here it is, an SVG calendar which always display's today's date.

(Note - GitHub doesn't allow data URIs or iFrames - so you'll need to click the link to see it)

The background image is derived from the Twitter TweMoji Calendar icon - CC-BY.

Use

SVG supports JavaScript. Browsers will only run the JavaScript if the SVG is included...

in an iframe <iframe src="calendar.svg"></iframe>
as inline <body><svg>.....</svg></body>

It will not run JavaScript in an <img> element.

HOWTO

Text support in SVG is a little awkward, so let me explain how I did this.

SVG supports JavaScript. This will run as soon as the image is loaded.

<svg onload="init(evt)" xmlns="http://www.w3.org/2000/svg"
aria-label="Calendar" role="img" viewBox="0 0 512 512">

Next step is to get the various date strings. I'm using the en-GB locale as that's where I'm based.

<script type="text/ecmascript"><![CDATA[
function init(evt) {
  var time = new Date();
  var locale = "en-gb";

I want to display something like "Sunday 25 FEB" - the locale options allow for short and long names. So you could have "SUN 25 February".

  var DD   = time.getDate();
  var DDDD = time.toLocaleString(locale, {weekday: "long"});
  var MMM = time.toLocaleString(locale,  {month:   "short"});

Finally, we need to add the text on to the image.

  var svgDocument = evt.target.ownerDocument;

  var dayNode = svgDocument.createTextNode(DD);
  svgDocument.getElementById("day").appendChild(dayNode);

  var weekdayNode = svgDocument.createTextNode(DDDD);
  svgDocument.getElementById("weekday").appendChild(weekdayNode);

  var monthNode = svgDocument.createTextNode(MMM.toUpperCase());
  svgDocument.getElementById("month").appendChild(monthNode);
  
}
]]></script>

Text positioning is relatively simplistic. An X & Y position which is anchored to the bottom of the text - remember that letters with descenders like g will extend beyond the bottom of the Y co-ordinate. This is also where we set the colour of the text, its size, and a font.

A monospace font makes it easier to predict the layout.

<text id="month"
  x="32" 
  y="164" 
  fill="#fff" 
  font-family="monospace"
  font-size="140px"
  style="text-anchor: left"></text>

A word on anchoring. To centre the anchor, use style="text-anchor: middle"

A quick test shows that this works on all desktop browsers and Android browsers. I've not tested on iPhones or anything more exotic.

Explanation

Result

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