Learning JavaScript

Chapter 13

1. The third, and optional, parameter of XMLHttpRequest.open is a Boolean value. Setting this to true, the default, the request is asynchronous; setting it to false makes the request synchronous.

2. After getting a reference to the XMLHttpRequest object and opening it, assign the callback function through the onReadyStateChange property.

3. The XMLHttpRequest object’s readyState property needs to have a value of 4 for completed; the request object’s HTTP status property should be 200 for a successful service request.

4. Here are the three formats: HTML, which can be immediately added to the page without any formatting; XML, which can be formatted with XSLT; and JSON, which can be used in a eval function call to create a web structure ready for processing.

5. From the Google Maps documentation, create a new GIcon object and populate its properties. Then use the object when creating the new GMarker object:

6. var icon = new GIcon(  );
   icon.image = "http://labs.google.com/ridefinder/images/mm_20_red.png";
   icon.shadow = "http://labs.google.com/ridefinder/images/mm_20_shadow.png";
   icon.iconSize = new GSize(12, 20);
   icon.shadowSize = new GSize(22, 20);
   icon.iconAnchor = new GPoint(6, 20);
   icon.infoWindowAnchor = new GPoint(5, 1);
   ...
   marker = new Gmarker(point,icon);