What do you mean
A. by "read" and what do you mean by
B "table text"?
And finally what do you mean by
C. application file?
A => writing the unformatted contents to a file?
B => an InDesign table?
C => an InDesign document?
If you have a table selected, you'll get the unformatted contents this way:
var myTableContents = app.selection.contents;
For all tables in one InDesign document (no nested tables, no tables in footnotes) you can get it by:
var allTablesContents = app.documents.stories.everyItem().tables.everyItem().contents;
The variable allTableContents will be an array of arrays.