grammar of expressions

[AnyON]

Hi all

Maybe I don't know something...
You can write an expression for the position of a layer in different ways. For example like this

var TargetL = thisComp.layer("GradComp")
[TargetL.width, TargetL.height]

or so

[thisComp.layer("GradComp").width, thisComp.layer("GradComp").height]

When you write it for the first time, the application shows an error

TypeError: Cannot read properties of undefined (reading 'width')

But with the second version of writing, such an error does not occur...

What is the difference???

[AnyON]

Be sure to end the token line with a semicolon (;)

[ShiveringCactus]

@AnyON has it right, the programming language in After Effects is a cut down version of Javascript.  Semicolons are used to end a statement in Javascript, as otherwise it reads as:

var TargetL = thisComp.layer("GradComp")[TargetL.width, TargetL.height]

Which AE would try to take as create a new variable, called TargetL and make it equal to a values in an array called thisComp.layer("GradComp") and those values are TargetL's width and height, which we've just made - in other words something not possible to process.