Photoshop script for Expand/Contract of Selection

Question

Hi!
I need script that will make Expand or Contract Selection for example 1px each time I hit keyboard shortcut. I mean I would like to use this options because I use it very often but I would like without dialog box when PS ask for value of expand/contract. When I will have script for those I could make it by wheel in my Intuos Pro. Now I can't because every time I have dialog box. Thanks in advance for help!
Regards
Arek

Answer 1

cool, thanks, the script works great!
#target photoshop
app.bringToFront();
try {
        // test for active selection
        if (hasSelection(app.activeDocument)) {
            // expand selection
            //app.activeDocument.selection.expand(new UnitValue (100, "px"))   
            // contract selection
            app.activeDocument.selection.contract(new UnitValue (100, "px"))
        else {
            alert ("ERROR: no active selection \n USAGE: the script requires an active selection")
catch (e) {
        alert ("ERROR: the script did not execute")
//////////// FUNCTIONS ////////////
function hasSelection(doc) {
  var res = false;
  var as = doc.activeHistoryState;
  doc.selection.deselect();
  if (as != doc.activeHistoryState) {
    res = true;
    doc.activeHistoryState = as;
    return res;