Urgent help

I guys i am trying to make Movie clip movement to infinite loop to x axis.
It should move like left to right on loop, without any jurk.
i used this code. this is working fine to move left, but i am not getting how should i make it move on looop.

this.onEnterFrame = function() {
	if (this.masked._x>-100) {
		this.masked._x += -10;
	} else {
		this.masked._x += 100;

any suggestion or help?
thanks for your time