Conditional resize image script for Photoshop. Creates thumbnail and large version and saves in JPEG.

imageResizeSave.jsx

var image = app.activeDocument;
var imageRatio = image.width / image.height;

// if your path has spaces you have to escape them, or use a path with no spaces
var folderThumbs = "/path/to/folder/thumbs";
var folderLarge = "/path/to/folder/large";

var thumbArea = {
      width: 700,
      height: 500
};

thumbArea.ratio = thumbArea.width / thumbArea.height;

var largeArea = {
      width: 2000,
      height: 1500
};

largeArea.ratio = largeArea.width / largeArea.height;

var saveOptions = new ExportOptionsSaveForWeb();
saveOptions.quality = 70;
saveOptions.format = SaveDocumentType.JPEG;
saveOptions.optimized = true;

// THUMBS
var scaleThumb;

if(imageRatio >= thumbArea.ratio){
      scaleThumb = thumbArea.width / image.width.value;
} else {
      scaleThumb = thumbArea.height / image.height.value;
}

// do not upscale
if (scaleThumb < 1) {
      image.resizeImage(UnitValue(image.width * scaleThumb,"px"),UnitValue(image.height * scaleThumb,"px"),null,ResampleMethod.AUTOMATIC);
}

image.exportDocument(File(folderThumbs + "/" + image.name),ExportType.SAVEFORWEB,saveOptions);

// we go back to initial state
image.activeHistoryState = image.historyStates[0];

// LARGE
var scaleLarge;

if(imageRatio >= largeArea.ratio){
      scaleLarge = largeArea.width / image.width.value;
} else {
      scaleLarge = largeArea.height / image.height.value;
}

// do not upscale
if (scaleLarge < 1) {
      image.resizeImage(UnitValue(image.width * scaleLarge,"px"),UnitValue(image.height * scaleLarge,"px"),null,ResampleMethod.AUTOMATIC);
}

image.exportDocument(File(folderLarge + "/" + image.name),ExportType.SAVEFORWEB,saveOptions);

image.close(SaveOptions.DONOTSAVECHANGES);

Check this GIST only for conditional resize
https://gist.github.com/PierBover/2748189c25dee4dfa195