The JavaScript files here are expressions for After Effects. Some I've developed, some are from colleagues and from the resource sites below. I've tried to credit the original author in the comments for each script.
Aside from the code here, there are a number of other resources to help you learn and implement expressions:
- MotionScript.com — legendary expressions and scripting resource by Dan Ebberts
- After Effects Expressions book by Marcus Geduld
- Adobe Expression Basics, Expression Language Reference, and Expression Examples
- Creative Cow After Effects Expressions Forum
- Adobe After Effects Expressions Forum
- AE Enhancers
- i2c After Effects Expressions Basics PDF by David Alex
- Introduction to Expressions by JJ Gifford — hasn't been updated since 2001, but much of it is still useful, especially his tables of properties that you can control with expressions.
- AExpr Breakdown
- Questions tagged
after-effects-expressionson the Video Production StackExchange
- In After Effects CC 2015 (13.5) or later (released 2015-06-26), Adobe has improved error handling in expressions. Go to After Effects CC > Preferences > General… and check the box for Enable JavaScript Debugger.
- Expressionist — Remco Janssen has written a new expression editor, that gives you a window inside AE with basic IDE features such as syntax highlighting, line numbers and multiple cursors. $40, released 2016-03-03.
- Paul Tuersley’s ExpressEdit is also a good option for managing expressions project-wide. $35.
Since Expressions are written in JavaScript, it's good to have a handle on the language.
- JavaScript: The Definitive Guide book by David Flanagan — excellent reference to the language
- MDN JavaScript Reference is a good online tool if you’re not near your book.
- Codecademy has a free online class in learning JavaScript. Many of its examples are tied to the web, but learning how to write more object-oriented Javascript can be very helpful for complicated expressions.
Similar to Expressions, but for scripting the After Effects app itself, vs. a value in a composition. Still uses JavaScript as the basis for the language, so once you know one, the other isn't far off.
- Adobe After Effects Developer Center, including Scripting Guides. As of this writing, CS6 is the last full guide, and there are a few “New in [Version X]” documents as addendums for CC and beyond.
- Adobe After Effects Scripting Forum
- aescripts + aeplugins marketplace for people to sell (or give away) their scripts.
- Redefinery scripts by Jeff Almasol