var oText = document.getElementById("id_anim_text");
var oContainer = document.getElementById("id_anim_container");

var nWidth = oText.offsetWidth;
var nPos = oContainer.offsetWidth;

function OnTimer(){
	oText.style.left = nPos.toString() + "px";

	if(--nPos < -nWidth)
		nPos = oContainer.offsetWidth;
}

OnTimer();
window.setInterval(OnTimer, 20);