findAll.jsx

(function(t,a,w,k,i,ff)
//----------------------------------
// InDesign script.
// Show Grep/Text found items into a file.
{
    a = (t||0)&&('string'==typeof(app[(k='findGrep')+'Preferences'].findWhat)||'string'==typeof(app[(k='findText')+'Preferences'].findWhat));
    if(!a ) return;

    w = new Window('palette',k);
    w.margins = 25;
    (w.add('staticText',void 0,"Running " + k + "...")).preferredSize=[250,22];
    w.show();
    w.update();

    if( !(a=t[k]()) || !(i=a.length) ){ w.hide(); alert("No result"); return; }
    w.children[0].text = "Processing "+i+" found items...";
    for( ; i-- ; a[i]=a[i].contents );
    
    ff = File(File(Folder.temp) + '/' + k + '.txt');
    ff.open('w') && (ff.encoding='UTF8',ff.write(a.join('W'==ff.lineFeed[0]?'\r\n':'\n')),ff.close(),ff.execute());

})(app.properties.activeDocument);

The finalized (and enhanced) snippet is now available in my IdGoodies repo:

• See DocGrepTextFindAll.jsx