var MARKER_CONST = "###I#AM#THE#TOC#TEXTFRAME###"; 
 
[..] 
var firstPage = null; 
 
var tocExists = (doc.textFrames.item(MARKER_CONST) != null); 
if(tocExists) { 
	firstPage = doc.textFrames.item(MARKER_CONST).parent; 
	assert(newFirstPage instanceof Page, "...error..."); 
} 
else { 
	firstPage = doc.pages.add(LocationOptions.BEFORE, doc.pages[0]); 
} 
 
[..] 
var tocStories = doc.createTOC(myTocStyle, true); 
var tocTextframe = tocStories[0].texts[0].parentTextFrames[0]; 
tocTextframe.label = MARKER_CONST;