Build Date in Footer

A quick post on how I added a build date to the footer of this website.

image/svg+xml Openclipart Simple Horizontal Rule 1 2012-10-13T19:58:51 Simple horizontal rule designed to be used in a programme/ending of a chapter. Based on one seen in an out of copyright book called "The universe: or, The infinitely great and the infinitely small". https://openclipart.org/detail/172738/simple-horizontal-rule-1-by-nasfarley88-172738 nasfarley88 decoration horizontal rule

This post assumes the following:

  • You know what a package.json file is
  • You know what a build script is
  • You know what a static site generator is
  • You know what a footer is

If you don't know what any of those things are, I recommend you read up on them before continuing.

The Problem

I wanted to add a build date to the footer of this website, in the format of YYYY-MM-DD. It would update every time a new build was made and deployed.

The Solution

I added a line of code in the build script that saves the date to a global variable, and then used that variable in the footer.

The Code

package.json
{
    "scripts": {
      "build": "eleventy"
    }
}

the build script is modified as

package.json
{
  "build": "BUILD_DATE=$(TZ='America/Los_Angeles' date +'%d %B %Y') eleventy"
}

In the footer, the {{ BUILD_DATE }} variable can be used in double curly brackets.

src/_includes/footer.njk
<footer>
    <p>Build Date: {{ BUILD_DATE }}</p>
</footer>

will render

src/_includes/footer.njk
<footer>
    <p>Build Date: 27 October 2023</p>
</footer>

The Explanation

The BUILD_DATE variable is set to the output of the date command, which is a Unix command that prints the current date and time. The TZ flag sets the timezone to the one specified, in this case, America/Los_Angeles. The + flag specifies the format of the output, which is '%d %B %Y' in this case. The %d is the day of the month, %B is the full month name, and %Y is the full year.

Find the correct timezone by referring to the Wikipedia entry.

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