Create a template function library

Rather than put all your code into the publican.config.js configuration file, you can create reusable function libraries in other files. The functions these libraries export can be appended to the global tacs object.

Create a function library #

The following example creates a new lib/format.js file containing formatting functions:

• A private cDate() function converts any value to a date.
• A public dateYear() function returns the four-digit year of any date.

lib/format.js

// create a date
function cDate(d) {
  d = new Date(d);
  return +d && !isNaN(d) && d instanceof Date ? d : new Date();
}

// date year, e.g. "2025"
export function dateYear( d ) {
  return cDate(d).getUTCFullYear();
}

Import the library #

You can import the public formatting functions into your publican.config.js configuration file. The following code appends them as child properties of the tacs.fn.format object:

publican.config.js excerpt

import { Publican, tacs } from 'publican';
import * as fnFormat from './lib/format.js';

const publican = new Publican();

// set global defaults
tacs.config = tacs.config || {};
tacs.config.language = 'en-US';

// append formatting functions
tacs.fn = tacs.fn || {};
tacs.fn.format = fnFormat;

// build site
await publican.build();

Use in content and templates #

A function named tacs.fn.format.dateYear() is now available to content and templates, e.g.

<!-- the year the post was written -->
<p><em>Post written in ${ tacs.fn.format.dateYear( data.date ) }.</em></p>

<!-- the year the site was built -->
<p><em>&copy;${ tacs.fn.format.dateYear() }</em></p>

The result:

Post written in 2025.

©2025