How to keep a value in a if/else condition

Hi,

I'm a newbie in after effect and I'm playing with expressions. I want a value to be updates if the condition is meet, but to keep the value if not.
Thanks

if (transform.position[2] > -1) {
-keep the value. (do nothing)
} else {
text.animator("Animator 1").selector("Range Selector 1").offset
};