Pikaday JS How to use full day and month names for input format without moment js

I'm using Pikaday.js like so:

new Pikaday({
            field: document.getElementById('top-banner-datepicker'),
            minDate: new Date()

I know that the answer lies in this example from the documentation:

var picker = new Pikaday({
    field: document.getElementById('datepicker'),
    format: 'D/M/YYYY',
    toString(date, format) {
        // you should do formatting based on the passed format,
        // but we will just return 'D/M/YYYY' for simplicity
        const day = date.getDate();
        const month = date.getMonth() + 1;
        const year = date.getFullYear();
        return `${day}/${month}/${year}`;
    },
    parse(dateString, format) {
        // dateString is the result of `toString` method
        const parts = dateString.split('/');
        const day = parseInt(parts[0], 10);
        const month = parseInt(parts[1], 10) - 1;
        const year = parseInt(parts[2], 10);
        return new Date(year, month, day);
    }
});

But I can't figure out how to use full day (Monday, Tuesday, Wednesday, etc) and full month names (January, February, etc) instead of the abbreviations (Mon, Tue, Wed... Jan, Feb, Mar... etc)

I don't want to use Moment.JS as it's a giant dependency.

Any help much appreciated!

Thank you

If you wish to format the datepicker field you could use toLocaleString().

For example if you want to get October instead of Oct:

date.toLocaleString('default', {
      month: 'long' // use localestring month to get the long month
});

And if you want to get Sunday instead of Sun:

date.toLocaleString('default', { // use localestring weekday to get the long day
      weekday: 'long'
});

Example snippet:

var picker = new Pikaday({
  field: document.getElementById('datepicker'),
  firstDay: 1,
  minDate: new Date(),
  maxDate: new Date(2020, 12, 31),
  yearRange: [2000, 2020],
  format: 'D-M-YYYY',
  toString(date, format) {
    console.log(date.toLocaleString('default', {
      weekday: 'short' // use localestring weekday to get the short abbv of day
    }));
    console.log(date.toLocaleString('default', {
      month: 'short' // use localestring weekday to get the short abbv of month
    }));
    // you should do formatting based on the passed format,
    // but we will just return 'D/M/YYYY' for simplicity
    const day = date.getDate();
    const daylong = date.toLocaleString('default', { // use localestring weekday to get the long day
      weekday: 'long'
    });
    const month = date.getMonth() + 1;
    const monthlong = date.toLocaleString('default', {
      month: 'long' // use localestring month to get the long month
    });
    const year = date.getFullYear();
    return `${daylong}, ${monthlong}, ${day} ${year}`; // just format as you wish
  }
});

#datepicker {
  width: 200px;
}

<link href="https://pikaday.com/css/pikaday.css" rel="stylesheet" />
<script src="https://pikaday.com/pikaday.js"></script>
<label for="datepicker">Date:</label>
<input type="text" id="datepicker">