Create/find tables and apply style

Question

Hello,
I'm very new to scripting. I want to learn the basics like creating a table, creating anchored frames, textframes, etc.
Now, I want to create/find tables in a document and I would like to apply styles. I saw a script to do this. When I paste the script in Extendscript CS4, than the program crash.
The program crash in part 1. When I create another script with only part 2 (see //part 2) then there is no problem.
What do i wrong? And can anyone tell me what part 1 of the script do?
Thanks,
// part 1
// using your version; I'd prefer to return 0 if table not found
function findTable(obj) {
         while (obj.constructor.name != "Table") {
        obj = obj.parent;
        if (obj.constructor.name == "Application") {
            throw "Can't find table"
    return obj
// part 2
var myTable = 0;
if (app.documents.length > 0 && app.selection.length > 0)
    myTable = findTable(app.selection[0]);
// check for at least enough rows for 1 top row, 1 body row, 1 bottom row
if (myTable != 0 && myTable.rows.length >= 3) {
    // delete all rules; set insets to 0
    myTable.cells.everyItem().appliedCellStyle = "[None]";
    // format bottom row
    // (remember rows uses 0-based count)
    a = myTable.rows.length - 1;
    myTable.rows[a].cells.everyItem().appliedCellStyle = "4.cell_body_last";
    // format middle rows
    first = 1;
     last = myTable.rows.length - 2;
    for (a = first; a <= last; ++a)
        myTable.rows[a].cells.everyItem().appliedCellStyle = "3.cell_body";
    // format top row
    a = 0;
    myTable.rows[a].cells.everyItem().appliedCellStyle = "2.cell_header";

Answer 1

Part 1 expects the text cursor to be anywhere inside a table -- either in the regular text, or with a cell, row, column, or the entire table selected.
It walks "up" using its parent until it arrives at the table object itself.
This will only work if the text cursor actually is anywhere inside a table. It does nothing when you are somewhere else, and it only works with the "current" table.