Brendan Eich has released a posting on Mozilla 2 in which he looks back at Mozilla 1 before pointing the new way.

This jumped out at me immediately:

For Mozilla 2, we will have a JIT-oriented JavaScript VM (details soon) that supports the forthcoming ECMAScript Edition 4 (”JS2″) language. Among the desirable characteristics of this VM will be a conservative, incremental garbage collector (GC). If it makes sense, we can use this GC module to manage DOM object memory instead of using XPCOM reference counting. We can use its conservative scanning code to assist in cycle collection. And we can JIT calls directly into DOM glue code entry points (provided no JS mutation has overridden a method property value), bypassing the powerful but relatively slow typelib-based dispatching machinery of XPConnect.

This will kick Ajax performance in Firefox up a notch or three.

and:

I haven’t really begun to talk about further graphics work (3D canvas) and security models (those safe browser-based mashups). Nor have I begun to discuss Firefox 4, the likely version to be based on Mozilla 2, except to say that we will keep an unbranded Firefox version building at all times as Mozilla 2 is developed. Mainly I am focusing on the Mozilla platform, on which Firefox, its add-ons, and other apps all stand or fall.

So the goals for Mozilla 2 are:

  • Clean up our APIs to be fewer, better, and “on the outside.”
  • Simplify the Mozilla codebase to make it smaller, faster, and easier to approach and maintain.
  • Take advantage of standard language features and fast paths instead of XPCOM and ad hoc code.
  • Optimization including JIT compilation for JS2 with very fast DOM access and low memory costs.
  • Tool-time and runtime enforcement of important safety properties.

Exciting stuff. And this will push the other browsers to give us more of the same. There is also a lot more detail in the posting itself, including fun C++ code, and thoughts on where we will be with graphics.

I can’t wait to see Brendan give his keynote at The Ajax Experience in just over a week to hear more.