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Programmatically generates text that will be displayed on the calendar’s column headings.

function( date ) -> string

This function will will receive a date object that represents a single column’s date and must return a string to be displayed. The text will be escaped before being inserted into the DOM. You do not need to worry about escaping HTML entities.


var calendar = new Calendar(calendarEl, {
  columnHeaderText: function(date) {
    if (date.getDay() === 5) {
      return 'Friday!';
    } else {
      return date.toString();

If you are simply stringifying a date with a formatting string, using columnHeaderFormat is more elegant.

If you need to generate HTML, use columnHeaderHtml instead.