How to use if statement with var?

you can't declare a new variable when using an if statement

 var activated : boolean = false;
 
 function Update(){
   if(activated){
     ...
   }
 }

Several small mistakes here. As unluckyBastard pointed out, you cannot declare a variable inside a condition, it makes sense, if you think about it...

Also, you're using a single equal symbol '=' which will assign a value rather than compare. You mean to use '=='.

Lastly, the statement to evaluate in a condition must be in-between parenthesis. Hence your code could look like this:

 var Activate = true;
 if(Activate==true){
     //do something
 }

OR(cleaner)

 var activate:boolean = true;
 if(activate){
     //do something
 }

Thanks unluckyBastard and BY0LOG1C.