Question

I’m looking at the autocomplete tutorial, and I have a few questions: http://jqueryui.com/demos/autocomplete/#option-disabled

$( "#tags" )
            // don't navigate away from the field on tab when selecting an item
            .bind( "keydown", function( event ) {
                if ( event.keyCode === $.ui.keyCode.TAB &&
                        $( this ).data( "autocomplete" ).menu.active ) {
                    event.preventDefault();
                }
            })
            .autocomplete({
                minLength: 0,
                source: function( request, response ) {
                    // delegate back to autocomplete, but extract the last term
                    response( $.ui.autocomplete.filter(
                        availableTags, extractLast( request.term ) ) );
                },
                focus: function() {
                    // prevent value inserted on focus
                    return false;
                },
                select: function( event, ui ) {
                    var terms = split( this.value );
                    // remove the current input
                    terms.pop();
                    // add the selected item
                    terms.push( ui.item.value );
                    // add placeholder to get the comma-and-space at the end
                    terms.push( "" );
                    this.value = terms.join( ", " );
                    return false;
                }
            });

So I understand the parameters for source is request and response. Are these reserved keywords? I couldn’t find anything when typing this into google. I am unclear as to what is the request and response being passed into here. Is the request just grabbing the input? Where can I read up more on this?

Answer 1

request and response are simply the names that the author of the code has chosen to give to the two formal parameters of the callback assigned to the source option of the autocomplete widget:

Autocomplete can be customized to work with various data sources, by just specifying the source option. A data source can be:

• an Array with local data
• a String, specifying a URL
• a Callback

The third variation, the callback, provides the most flexibility, and
can be used to connect any data source to Autocomplete. The callback
gets two arguments:

• A request object, with a single property called "term", which refers
  to the value currently in the text input. For example, when the user
  entered "new yo" in a city field, the Autocomplete term will equal
  "new yo".
• A response callback, which expects a single argument to
  contain the data to suggest to the user. This data should be filtered
  based on the provided term, and can be in any of the formats described
  above for simple local data (String-Array or Object-Array with
  label/value/both properties). It’s important when providing a custom
  source callback to handle errors during the request. You must always
  call the response callback even if you encounter an error. This
  ensures that the widget always has the correct state.