what is the problem ?

[Fares2219774080uj]

[OussK · Accepted solution]

You should use the if-else in the proper way, like the one below
If () {
} else {
}
or if you want to keep using it in the old way you should change the expression settings to a legacy from the project settings

[Fares2219774080uj]

can u write the expressions in write way, pls ? 

[Fares2219774080uj]

can you write the expression in the right form ?

[ShiveringCactus]

I think OussK is suggesting this approach:

If (textIndex % 2) {
//do something
} else {
// do something else
}

The trouble with Javascript is that (quite often), you can take shortcuts with your code.  Personally, I find these make it much harder to debug, unless you're familiar with the coding style.  By spelling everything out more, it is easier for someone else to identify what's going on.

As far as I know, AE should have been able to process the original line, but it couldn't so the solution above should work. 

Or as OousK also suggested, it might be the project's Expression Engine, which you can find in File > Project Settings

[Fares2219774080uj]

it worked well wheni changed it to legacy extended script