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

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