keoshi.com blog

If I have one complaint about Photoshop it's the lack of a Save All option. It seems it's logical that Adobe would implement it, given the large photo consumer base.
Picture yourself coming from a photo shoot and there you have 16GB of files to edit. Would you also want to save one by one? We've all been there and I think not.

Photoshop makes up for that by supporting event-based scripts in several languages: Javascript, VBScript and AppleScript. These scripts will automatically instruct Photoshop what to do, you just have to press the button.

I've searched around and found this interesting topic on kirupa.com.
This snippet was originally written by mlk (mlkdesign -at -online.fr) with a few tweaks by yours truly. Here's the code for the Save All script, both in Windows and Mac flavors respectively.

Windows

var tempFolder = new Folder ("C:/Your_Temporary_Folder")
tempFolder.create();
var DL = documents.length;
for(a=1;a<=DL;a++){
   activeDocument = documents[a-1];
   var AD=activeDocument;
   var imgName= AD.name;
   imgName = imgName.substr(0, imgName.length -4);
   AD.flatten();
   saveFile = new File("C:/Your_Temporary_Folder/"+imgName+".jpg");
   saveOptions = new JPEGSaveOptions();
   saveOptions.embedColorProfile = true;
   saveOptions.formatOptions = FormatOptions.STANDARDBASELINE;
   saveOptions.matte = MatteType.NONE;
   saveOptions.quality = 12;
   AD.saveAs(saveFile, saveOptions, true,Extension.LOWERCASE);
}

Mac OS

var tempFolder = new Folder ("/YOUR_VOLUME_NAME/Users/YOUR_USERNAME/Documents/temp")
tempFolder.create();
var DL = documents.length;
for(a=1;a<=DL;a++){
   activeDocument = documents[a-1];
   var AD=activeDocument;
   var imgName= AD.name;
   imgName = imgName.substr(0, imgName.length -4);
   AD.flatten();
   saveFile = new File("/YOUR_VOLUME_NAME/Users/YOUR_USERNAME/Documents/temp"+imgName+".jpg");
   saveOptions = new JPEGSaveOptions();
   saveOptions.embedColorProfile = true;
   saveOptions.formatOptions = FormatOptions.STANDARDBASELINE;
   saveOptions.matte = MatteType.NONE;
   saveOptions.quality = 12;
   AD.saveAs(saveFile, saveOptions, true,Extension.LOWERCASE);
}

Copy and paste the code above to your favorite text editor, edit the highlighted bits according to your system and preferences (both the path and JPEG quality) and save the file with a .js extension. To use it open the saved file on Photoshop through the menu File > Scripts.
This example saves JPEG files but you can change that as well to better suit your needs — perhaps PNG is your thing — but of course some of the parameters have to be re-written.

I use this script all the time and once you use it too you won't understand how you managed without it in the first place.