Adobe acrobat DC - Add footer with bookmark text

bookmarkToFooterAdobeDC.js

var aRect = [];
//Hard coded values for bottom left corner of A4 page
aRect[0] = 24.218078613281250;
aRect[1] = 45.985595703125;
aRect[2] = 485.0216979980469;
aRect[3] = 10.20367431640625;

//Page number that bookmark maps to
var a = [];
//Bookmark name, corresponding to array a
var b = [];
for(var i = 0; i < this.bookmarkRoot.children.length; i++){
    this.bookmarkRoot.children[i].execute();
    a.push(this.pageNum);
    b.push(this.bookmarkRoot.children[i].name);
}
//Jump back to first bookmark page
this.bookmarkRoot.children[0].execute();

var markNr;
var mark;

var nextNr = a.shift();
var nextMark = b.shift();
for (var p = 0; p < this.numPages; p++) {
	if(p >= nextNr){
		markNr = nextNr;
		mark = nextMark;
		if(a.length > 0) { 
			nextNr = a.shift(); 
			nextMark = b.shift();
		}
	}

    var f = this.addField("footerPage"+p, "text", p, aRect )
    f.delay = true;
    f.borderStyle = border.s;
    f.lineWidth = 0;
    f.readonly = true;
    f.value = mark;
    f.doNotSpellCheck = true;
    f.textSize = 10; // Auto-sized
    f.delay = false;
}

When I paste this in to the Adobe debug console I get an error 'undefined'. How is this code to be used? Thanks in advance.