Question

I am looking at jquery.ui-1.8.11.js:

$.extend(Datepicker.prototype, {
    /* Class name added to elements to indicate already configured with a date picker. */
    markerClassName: 'hasDatepicker',

    /* Debug logging (if enabled). */
    log: function () {
        if (this.debug)
            console.log.apply('', arguments);
    },

What is that log: function() syntax? What’s it called? How can it be used?

Answer 1

The second argument to an $.extend call is an Object. They’re defined using curly braces {} and take key: value pairs. The value can be a function, which is what is happening for the log.

This is analogous to the following:

var myObject = {
  prop1: 'some value',
  prop2: 'some other value',
  method1: function () {
    // some code here.
  }
}

You can later call myObject.method1() to perform whatever the code inside the function is.