Latest revision as of 16:26, 1 May 2020

Javascript for After Effects[]

These are standard and common functions used by After Effects. Although many can be used in an Expressions field, all of these are accessable by running a script manually.

Types of scripts[]

There are two basic types of scripts which AE uses, uncompiled and compiled.

Uncompiled Javascript[]

An uncompiled Javascriptis the most common script you'll see. These are the scripts have filenames ending in .jsx and can be opened with any text editor and edited, and you can see the javascript code when opened. These scripts are meant to be flexible and available for anyone to edit.

Compiled Javascript[]

Compiled scripts work exactly like an uncompiled script only the file is encoded for protection. These types of scripts are meant for commercial distribution and cannot be edited by anyone but the author.

Variables[]

What are they?

You can think of a variable as a box that can store different types things based on the boxes shape. For example, a number box (variable) can store numbers. A string box can store a string of numbers and sletters surrounded by quotes "". Normally we create a box before refering to it. You wouldn't normally tell someone to give you a plooper unless you told that person what a plooper is. ex. "A plooper is the number 5. can you tell me what a plooper is?". then answer would be, "The number 5" Establishing the existance of your variable in this manner is called declaration. You must declare your variable before using it.

Declaring variables

Variables can be declared with a "var" in front of them. ex "var myNumber". you can also assign a value to your variable at the same time. "var myNumber = 5" Until a variable is assign a value (5) it is considered "undefined." Variable should be uniquely named. If you accidently try to declare a variable that already exists, it will be treated as a an assignment and assign any new value in the declaration statement to the variable. If the duplicate declaration has no assignment, then nothing happens. If you try to assign a value to a non-existent variable, JavaScript will create the variable for you.

Conventions

When naming your variable, you must use letters, $, and _ ex. "myPlooper" or "my_Plooper" or "$myPlooper"
never use spaces
Javascript is case-sensitive, meaning. "Plooper" is different from "plooper"
Try to use camelCase

Lifespan

The life of a variable is based upon the region in which is was declared. if it was declared inside a funtion, it doesn't exist outside the function. if it exists inside a loop, is does not exist outside the loop. Variables declared outside all loops and functions are considered global and exist while the script is being evaluated.

Escape Characters[]

Code	Char	Output
\'	'	single quote
\"	"	double quote
\\	\	backslash
\b		backspace
\f		form feed
\n		new line
\r		carriage return
\t		tab

Operators[]

Comparison Operators[]

**Comparison Operators**
Operator	Description	Example ( x=3 )	Result
==	Is equal to ( never use a single = )	x==5	false
===	vcvcv absolutely equal to (this checks variable type too)*	x===3 x==="3"	true false
!=	Is not equal to	x!=4	true
!==	is NOT equal to (this checks variable type too)*	x!==3 x!=="3"	false true
>	Is greater than	x>5	false
<	Is less than	x<5	true
>=	Is greater than or equal to	x>=5	false
<=	Is less than or equal to	x<=5	true

Logical Operators[]

**Logical Operators**
Operator	Description	Example ( x=3 )	Result
&&	and	( x>1 )&&( x-1>1 )	true
\|\|	or	( x==3 ) \|\| ( x="three" )	true
!	is not	!(x==3)	false

Arithmetic Operators[]

**Arithmetic Operators**
Operator	Description	Example ( x=3 )	Result
+	Add	x = x+2	x = 5
-	Subtract	x = x-2	x = 1
*	Multiply	x = x*2	x = 6
/	Divide	x = x / 2	x = 1.5
++	Increment by Increment (by 1) then return Return then increment (by 1)	x ++ 2 ++ x x ++	x = 5 x = 4 x = 3 (next time it will = 4)
--	Decrement by Decrement (by 1) then return Return then decrement (by 1)	x -- 2 -- x x --	x = 1 x = 2 x = 3 (next time it will = 2)
%	Divide and get remainder (Modulus)	x % 2	x = 1

Assignment Operators[]

**Assignment Operators**
Operator	Description	Example ( x=3 )	Result
=	Assigns a value	x = 5	x = 5
+=	adds a value	x += 5	x = 8
-=	subtracts a value	x -= 5	x = -2
*=	multiplies a value	x *= 5	x = 15
/=	Divides by a value	x /= 5	x = 0.6
%=	Divides and gets remainder of a value (Modulus)	x %= 5	x = 3

Event Handler[]

The following are NOT supported by AE at this time.

onAbort
onBlur
onChange
onClick
onDblClick
onDragDrop
onError
onFocus
onKeyDown
onKeyPress
onKeyUp
onload
onMouseDown
onMouseMove
onMouseOut
onMouseOver
onMouseUp
onMove
onReset
onResize
onSelect
onSubmit
onUnload

Methods[]

Dialogs[]

Name	Secure	Expression	Description
alert()	yes	no	Brings up an OK dialog, used to send the user a message.
confirm()	yes	no	Brings up an ok / cancel dialog and returned the value as a boolean.(good for if statements)
Error()	yes	no	Brings up an error dialog.
prompt()	yes	no	Brings up an ok / cancel dialog asking for user input. If no input is entered, the dialog returns false.

Math[]

Name	Secure	Expression	Description
isNaN()	yes	yes	Checks if a value is Not a Number.
Math.sqrt()	yes	yes	Finds the square root of a number.

String Object[]

new String(string)

charAt() Returns an index of a specified character position
charCodeAt() Returns the UNICODE value of a specified character at position
concat() Joins two or more strings together into one
fromCharCode() Converts UNICODE values into characters
indexOf() Finds the first occurance of a string or character and returns its index value of its location. If the string is not found 0 is returned.
lastIndexOf() Finds the last occurance of a string or character and returns its index value of its location. If the string is not found 0 is returned.
match() Searches a string for a substring, then returns any matches
replace() Searches a string for a substring, then replaces any matches with a new string
search() Searches a string for a substring, then returns the position of any matches
slice() Extracts a part of a string and returns a new string
split() Creates a substring of a specified string
substr() Extracts the characters from a string, beginning at a specified start position, and through the specified number of character
substring() Extracts the characters from a string, between two specified indices
toLowerCase() Converts a string to lowercase letters
toUpperCase() Converts a string to uppercase letters
valueOf() Returns the primitive value of a String object

toString() Converts a value into a string

String Object Properties

.Constructor - a reference to the function which created the object
.Length - returns the number of characters in a string
.Prototype - Allows you to add methods and properties to the sring object

Objects and Properties[]

An Object can be a File, project, folder, comp, layer, effect, etc. Each Object has a set of Properties; a file has a name, a layer has potition and rotation. Below are Objects and a few of their possible properties. In After Effects a specific object hierarchy is used. Meaning that objects contain sub-objects as well as properties.

application - app
- settings
- project
  - renderQueue
    - renderQueueitem(s)
      - outputModule(s)
  - compItem
    - layer(s)
      - properties
    - proxySource
      - solidSource
        color
      - placeholderSource
      - fileSource
        file
  - footageItem
    - mainSource
      - solidSource
        color
      - placeholderSource
      - fileSource
        file
    - proxySource
      - solidSource
        color
      - placeholderSource
      - fileSource
        file
  - folderItem
    - item(s)

system
file
folder
socket

Classic Javascript Objects

Anchor
Applet
Area
Array
Boolean
Button
Checkbox
Date
Document
Event
FileUpload
Form
Frame
Function
Hidden
History
Image
Layer
Math
Object
Reset
Screen
String
Submit
Text
Textarea
Window
Link
Location
Navigator
Number
Option
Password
Radio
RegExp
Select

Special[]

+ Used between to strings to quickly concatinate them together - instead of using the concat() method. You can also add with "+=".
,
?:
delete
new
this is a context dependand object or property. It's connected to whatever is being passed to a function.
typeof
void

Statements[]

try is like an if statement for errors. Everything in a try block will be executed and but if errors occur, catch statements can pick up the error and parse it.
throw will send an error out for a catch statement.
- catch looks for try or thrown errors and reports them.
if checks a true / false condition and executed if true.
- else
- switch looks up a value like an "if" statement would, but handles multiple results. This is like using a series of elseIf statements.
do
- while
for
- for-in
continue
break
export
import
label
return
var
with

Constants[]

Main Index
Infinity
NaN
undefined
null

Commenting[]

// - Single line comment

/* */ - Book ends for a multi-line comment

Changes: After Effects Javascript API