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Last updated 12/21/2009
Expression language reference
Use the After Effects expression elements along with standard JavaScript elements to write your expressions. You can
use the Expression Language menu at any time to insert methods and attributes into an expression, and you can use
the pick whip at any time to insert properties.
If an argument description contains an equal sign (
uses the included default value if you don't specify a different value.
Some argument descriptions include a number in square brackets—this number indicates the dimension of the
expected property or Array.
Some return-value descriptions include a number in square brackets—this number specifies the dimension of the
returned property or Array. If a specific dimension is not included, the dimension of the returned Array depends on
the dimension of the input.
The
W3Schools JavaScript reference website
pages for the JavaScript
Math
More Help topics
"Expression
basics" on page 646
"Expression
examples" on page 683
Global objects, attributes, and methods (expression reference)
Return type: Comp.
comp(name)
Argument type: name is a String.
Retrieves another composition by name.
Return type: Footage.
footage(name)
Argument type: name is a String.
Retrieves a footage item by name.
Return type: Comp.
thisComp
Represents the composition containing the expression.
Return type: Layer, Light, or Camera.
thisLayer
Represents the layer containing the expression. Because
example, you can start an expression with
Return type: Property.
thisProperty
Represents the property containing the expression. For example, if you write an expression on the Rotation property,
you can start an expression with
Return type: Number.
time
Represents the composition time, in seconds, at which the expression is being evaluated.
Return type: Number.
colorDepth
Returns the project color depth value. For example,
channel.
) and a value (such as
=
provides information for the standard JavaScript language, including
and
objects.
String
thisLayer.width
to refer to the Rotation property.
thisProperty
colorDepth
t=time
is the default object, its use is optional. For
thisLayer
or
and get the same result.
width
returns 16 when the project color depth is 16 bits per
USING AFTER EFFECTS CS4
Expressions
or
), then the argument
width=.2
660
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