Length of specific layer

Greetings everyone, 

I'm strugling with a problem for a script. 

My main goal was to export in a CSV files the names of the layers within a specific layer. 

My layers are as follow : 

• Texte
• Calque 1
  • Sub layer 1
  • Sub layer 2 
  • ...
• Text
  • 1
  • 1
  • 1
  • 2
  • 2
  • 3
  • 3
  • 3
  • 5
  • 5
  • 5
  • 5
  • 6
  • ...
• PUCES
• CALQUES

I want it to export the names of the layers from the layer "Text", so 1;1;1;2;2;3;3;3;3;5....

The script I used is as following, inspired by a fellow scripter on the web : 

#target illustrator

main();
function main(){

if(!documents.length) return;

var doc = app.activeDocument;
var docTitle = doc.name;
var docTitle = docTitle.substring(0, docTitle.length - 3);
var textFile = File('~/Desktop/Tests/' + docTitle + '_Layers.csv');
var docText = '';

var TEXTLayer = doc.layers.getByName("Text");
var TEXTLength = doc.layers.getByName("Text").length;

for (var i = 0; i < doc.layers.length; i++) {
var currentLayer = doc.layers[i]; 
docText += docTitle +';' + currentLayer.name + '\r';
}

textFile.open('e');
textFile.write(docText);
textFile.close();
}

This script works perfectly for the top layers of my document (here Texte, Calque 1, Text, PUCES and CALQUES ). 

But whe I apply the function below to the var "TextLayer" with the getByName method, to get the layers of the layer "Text" : 

for (var i = 0; i < TEXTLength; i++) {
var currentLayer = TEXTLayer.layers[i];
docText += docTitle +';' + currentLayer.name + '\r';

It doesn't work. 

I tried to dig up what the problem could be and it appears that TEXTLength is undefined ... 

Same apply if I try to get the length of the other top layers (Texte, Calque 1 ...). 

Is it a problem in the writing ? In the properties of the layers/sublayers? Or something else ? 

I'm quite new to Javascript so that doesn't help ... ^^'

Many thanks in advance for your help !