Extendscript to change font size in table

Well, Suryanarayanan_21, the font business is not that transparent.

Modiying the ¶ format just does this in the catalogue. Hence afterward you need to run through the table and assign the modified format to the cell paragraphs:

// table_font_change.jsx
// Document must be active !
// Only the first table in document is handled - and in this only the first ¶ in cells
#target framemaker
main ();                                          // ease debugging

function main () {
var oDoc, oFlow, oTbl, textItems, tblColWidths, textDocument, PT, FontSize, oPgfFmt;
  PT = 65536;                                     // use a named constant
  oDoc = app.ActiveDoc;
  oFlow = oDoc.MainFlowInDoc;
  textItems = oFlow.GetText(Constants.FTI_TblAnchor);
// Set the column widths
  for (var i = 0; i < textItems.len; i += 1) {
    oTbl = textItems[i].obj;
    tblColWidths = new Metrics (5 * 15 * PT, 5 * 15 * PT, 5*25*PT, 5*35*PT, 5*15*PT);
    oTbl.TblColWidths = tblColWidths;
  }
// Change font for the paragraph format CellBody (this changes the catalogue only)
  oPgfFmt = oDoc.GetNamedPgfFmt("CellBody");  
  if (oPgfFmt.ObjectValid()) {  
    oPgfFmt.FontFamily = GetFontFamilyIndex ("Arial"); 
    oPgfFmt.FontSize   = 8 * PT;
  }
// Apply the correct(ed) ¶ format to all cells
  SetTblCellParaFmt (oDoc, oTbl, "CellBody" );
}

function SetTblCellParaFmt (oDoc, oTbl, sPgfFmt ) { // == Apply ¶ to all cells in table ===========
// Arguments  oDoc    Current document
//            oTbl    Current table
//            sPgfFmt Paragraph format name to apply
// Returns   -
var oRow, oCell, oPgf;
  oRow = oTbl.FirstRowInTbl;
  while (oRow.ObjectValid()) {
    if (oRow.RowType === Constants.FV_ROW_HEADING || oRow.RowType === Constants.FV_ROW_FOOTING) {
      oRow = oRow.NextRowInTbl;  
      continue;
    }
    oCell = oRow.FirstCellInRow;
    while (oCell.ObjectValid()) {
      oPgf = oCell.FirstPgf;
      ApplyPgfFmt (oDoc, oPgf, sPgfFmt) 
      oCell = oCell.NextCellInRow;
    }
    oRow = oRow.NextRowInTbl;  
  }
} //--- end TblCurrBodyRowNum

function ApplyPgfFmt (oDoc, oPgf, sPgfFmt) { // === Apply paragraph format ========================
// Arguments  oDoc     Current document
//            oPgf     ¶ to get the new format
//            sPgfFmt  Name of pgf format to be applied
var oPgfFmt = 0, oProps;

  oPgfFmt = oDoc.GetNamedPgfFmt(sPgfFmt);  
  if (oPgfFmt.ObjectValid()) {  
    oProps = oPgfFmt.GetProps();  
    oPgf.SetProps(oProps);  
  } else {  
    oPgf.Name = sPgfFmt;                          
  }
} //--- end ApplyPgfFmt

function GetFontFamilyIndex (sName) { // === Get the index in FontFamilyNames =====================
// Arguments  sName    name of fontweight to be found (case indepently)
// Returns    Index of font families available in the current session; or null if not found
// Comment    The list of font families depends on your installation: On my it starts with
//            <Reserved>, Modern, Hobo Std, OCR A Std, Adobe Arabic, Adobe Devanagari, 
//            Adobe Hebrew, TeamViewer13, Barbedor FS, Barbedor FS Caps, Barbedor FS Med, 
//            Marlett, Arial, Arabic Transparent, ...
var j, aNames = app.FontFamilyNames;              // array
//for (j = 0; j < aNames.length; j++) {
//  $.writeln (aNames[j]);
//}
  j = GetIndexFromName (aNames, sName); 
  return j;
} //--- end Fgr_GetFontFamilyIndex  

function GetIndexFromName (aArray, sSearch) { //=== Get Index of of particular contents ===========
// Arguments  aArray   array of ini entries to be searched
//            sSearch  may be part of what to find - only first occurence in array element is found
// Returns    Index of found item - or null
// Comment    Character case and blanks are ignored in both source item and search item
//            aArray may contain placeholder null items which are ignored.
var j, jFound, saLen, sItem, sSearch;
  saLen     = aArray.length;
  sSearch   = sSearch.replace (" ", "");
  sSearch   = sSearch.toUpperCase();
  for (j = 0; j < saLen; j++) {
    if (aArray[j] != null) {
      sItem = aArray[j].toUpperCase();
      sItem   = sItem.replace (" ", "");
      jFound = sItem.indexOf(sSearch);
      if (sItem.indexOf(sSearch) == 0) { // found at the beginning
        return j;
      }
    }
  }
  return null;
} //--- end GetIndexFromName

BTW: I have never seen an assignment like this:

var FontSize = (8);

HTH Klaus Daube