Renumber _001 Suffix | Advanced File Renamer

function zeroPad(num, places) {
    var zero = places - num.toString().length + 1;
    return Array(+(zero > 0 && zero)).join("0") + num;
}

var parts = item.newBasename.match(/^(.+)_(\d+)$/);

if (app.global === undefined) {
  app.global = {};
}
if ( app.global[parts[1]] === undefined ) {
  app.global[parts[1]] = [];
}

app.global[parts[1]].push(parts[0]);

return parts[1] + '_' + zeroPad(app.global[parts[1]].length, 3);