Saving a png with photoshop script not working

Question

if (app.documents.length != 0) {
    var doc= app.activeDocument;

    for (i = 0; i < 5; i++) {
        var layer = doc.artLayers[0]
        layer.textItem.contents = i;

        var pngFile    = new File("/Users/dlokshin/temp/" + i + ".png");
        pngSaveOptions = new PNGSaveOptions();
        pngSaveOptions.interlaced = false;
        doc.saveAs(pngFile, pngSaveOptions, true, Extension.LOWERCASE);
    }
}

Whenever I run the script above, instead of saving the files as 1.png, 2.png, 3.png, etc it opens up the save dialogue box and prompts me to type in the file name and click save. What am I doing wrong?

Answer 1

Aparently saving a PNG is very different from saving a JPEG when scripting for photoshop. The below works for PNGs:

if (app.documents.length != 0) {
    var doc= app.activeDocument;

    for (i = 0; i < 5; i++) {
        var layer = doc.artLayers[0]
        layer.textItem.contents = i;

        var opts, file;
        opts = new ExportOptionsSaveForWeb();
        opts.format = SaveDocumentType.PNG;
        opts.PNG8 = false;
        opts.quality = 100;

        pngFile = new File("/Users/dlokshin/temp/speed.png");
        app.activeDocument.exportDocument(pngFile, ExportType.SAVEFORWEB, opts);
    }
}