Pro JavaScript Reading Notes1

The graded browser support chart provided by Yahoo

How to rate the browser?

Core JavaScript 1.5: The most current, accepted version of JavaScript. It has all the
features necessary to support fully functional object-oriented JavaScript. Internet
Explorer 5.0 doesn’t support full 1.5, which is the primary reason developers don’t like
to support it.
XML Document Object Model (DOM) 2: The standard for traversing HTML and XML
documents. This is absolutely essential for writing fast applications.
XMLHttpRequest: The backbone of Ajax—a simple layer for initiating remote HTTP
requests. All browsers support this object by default, except for Internet Explorer 5.5–6.0;
however, they each support initiating a comparable object using ActiveX.
CSS: An essential requirement for designing web pages. This may seem like an odd
requirement, but having CSS is essential for web application developers. Since every
modern browser supports CSS, it generally boils down to discrepancies in presentation
that cause the most problems. This is the primary reason Internet Explorer for Mac is
less frequently supported.