The Empty Statement
One final legal statement in JavaScript is the empty statement. It looks like this:
;Executing the empty statement obviously has no effect and performs no action. You might think that there would be little reason to ever use such a statement, but it turns out that the empty statement is occasionally useful when you want to create a loop that has an empty body. For example:
// initialize an array a for(i=0; i < a.length; a[i++] = 0) ;
To make your code clear, it can be useful to comment your empty statements as such:
for(i=0; i < a.length; a[i++] = 0) /* empty */ ;