Slices Save for Web Format

Have you checked the optimization settings for each individual slice?

In Photoshop’s Save for Web dialog, each slice can have its own export settings. Even if you select all slices, one or more slices may still be carrying a different optimization setting (such as PNG).

Try selecting the Slice Select Tool, click each slice, and verify that the format is set to JPEG in the Optimize panel before exporting. You can also try resetting the Save for Web settings or recreating the slices to see if the issue persists.

If possible, it would also help to know your Photoshop version and whether these slices were created manually or generated from guides/layers, as that may affect the behavior.

I've run into this before, and in my case it was because each slice can have its own export settings. Even if you choose JPEG in the Save for Web dialog, slices that were previously assigned PNG will keep that format unless you change them individually.

A few things to check:
- In Save for Web, select each slice (or Shift-select all slices) and make sure the preset actually changes to JPEG for all of them.
- If the slices were created from an older PSD or template, try deleting and recreating the slices, as they can retain old export settings.
- Make sure there aren't any Slice Options or optimization settings overriding the global export format.
- As a test, create a brand-new document, add a couple of slices, and see if they all export as JPEG. If they do, the issue is likely specific to that PSD rather than Photoshop itself.

It definitely feels like a long-standing quirk of Save for Web rather than expected behavior.

Thanks ​@Stephen Marsh I appreciate the time to create this post. The image format used to work “out of the box” when saving multiple slices. It doesn’t now. IMO...instead of relying on users to workaround Adobe’s fumble...Adobe should take steps to fix it.

The workaround I found is to select each slice individually using the Select Slice tool and Save for Web “selected Slices”. Then the  Save for Web > Image Format works as expected. Not ideal or efficient for an image with a bunch of slices, but it works.

 

The following script can be used to save all slices to file (JPEG, PNG, WEBP, PSD, TIFF).

/*
Save Slices to Files
Stephen Marsh
25th July 2026 - v1.0: Initial release
8th August 2026 - v1.1: Cleaned up the various save/export functions and preference variables. Added WebP Photoshop version support check.
10th August 2026 - v1.2: Added a "PNG (Save for Web)" export option, alongside the existing standard "PNG" Save As option.
https://community.adobe.com/questions-712/slices-save-for-web-format-1633676
Based on a script from jazz-y
https://community.adobe.com/t5/photoshop-ecosystem-discussions/script-for-splitting-multiple-psds-to-defined-slices/m-p/12592481
https://community.adobe.com/t5/photoshop-ecosystem-discussions/divide-my-image-to-layers/m-p/12467520
*/

#target photoshop

// Adjust the following "user friendly" variables as required. A GUI for these file format options isn't planned!

// JPEG (standard Save As)
var jpegEmbedColorProfile = true; // Boolean: true | false
var jpegFormatOptions = FormatOptions.STANDARDBASELINE; // FormatOptions.STANDARDBASELINE | FormatOptions.OPTIMIZEDBASELINE | FormatOptions.PROGRESSIVE
var jpegMatte = MatteType.NONE; // MatteType.NONE | MatteType.WHITE | MatteType.BLACK
var jpegQuality = 10; // Numeric: 0 - 12 (fallback if dialog quality is unavailable)

// JPEG (Save for Web)
var sfwIncludeProfile = true; // Boolean: true | false
var sfwInterlaced = 0; // 0 = false, 1 = true (ExportOptionsSaveForWeb uses numeric)
var sfwOptimized = true; // Boolean: true | false
var sfwQuality = 70; // Numeric: 0 - 100 (fallback if dialog quality is unavailable)

// PNG (standard Save As)
var pngCompression = 9; // Numeric: 0 - 9 (Smaller number = higher file size)
var pngInterlaced = false; // Boolean: true | false

// PNG (Save for Web)
var pngSfwPNG8 = false; // Boolean: true | false (false = PNG-24, true = PNG-8)
var pngSfwTransparency = true; // Boolean: true | false
var pngSfwInterlaced = false; // Boolean: true | false
var pngSfwQuality = 100; // Numeric: 0 - 100 (only relevant when pngSfwPNG8 is true)
var pngSfwIncludeProfile = true; // Boolean: true | false

// WEBP
// Compression type: "compressionLossless" | "compressionLossy"
// When "compressionLossy", quality (0-100) is taken from the dialog slider
var webpCompressionType = "compressionLossy";
var webpIncludeXMPData = true; // Boolean: true | false
var webpIncludeEXIFData = true; // Boolean: true | false
var webpIncludePsExtras = true; // Boolean: true | false
var webpSaveAsCopy = true;

// PSD
var embedColorProfile = true; // Boolean: true | false
var alphaChannels = true; // Boolean: true | false
var annotations = true; // Boolean: true | false
var spotColors = true; // Boolean: true | false

// TIFF
var tiffEmbedColorProfile = true; // Boolean: true | false
var tiffByteOrder = ByteOrder.IBM; // ByteOrder.MACOS | ByteOrder.IBM
var tiffTransparency = true; // Boolean: true | false
var tiffLayerCompression = LayerCompression.ZIP; // LayerCompression.RLE | LayerCompression.ZIP
var tiffInterleaveChannels = true; // Boolean: true | false
var tiffAlphaChannels = true; // Boolean: true | false
var tiffAnnotations = true; // Boolean: true | false
var tiffSpotColors = true; // Boolean: true | false
var tiffSaveImagePyramid = false; // Boolean: true | false
var tiffImageCompression = TIFFEncoding.TIFFLZW; // TIFFEncoding.NONE | TIFFEncoding.JPEG | TIFFEncoding.TIFFLZW | TIFFEncoding.TIFFZIP

//////////


main();

///// SCRIPTUI DIALOG - START /////
function showExportDialog() {
    var dlg = new Window("dialog", "Export Slices to Files (v1.2)");
    dlg.orientation = "column";
    dlg.alignChildren = "fill";
    dlg.spacing = 10;
    dlg.margins = 16;

    // Main panel/group holding all the export settings
    var mainPanel = dlg.add("panel", undefined, "Output Settings");
    mainPanel.orientation = "column";
    mainPanel.alignChildren = "left";
    mainPanel.spacing = 10;
    mainPanel.margins = [16, 20, 16, 16];

    // Row 1: folder picker button + statictext path (to the right of the button)
    var folderGroup = mainPanel.add("group");
    folderGroup.orientation = "row";
    folderGroup.alignChildren = "center";

    var chooseFolderBtn = folderGroup.add("button", undefined, "Choose Folder...");

    var pathText = folderGroup.add("statictext", undefined, "No folder selected", {
        truncate: "middle"
    });
    pathText.preferredSize.width = 320;

    // Row 2: subfolder checkbox
    var subfolderCheckbox = mainPanel.add("checkbox", undefined, "Automatically create \"JPEG Slices\" subfolder");
    subfolderCheckbox.value = true;

    // Row 3: File Format dropdown
    var formatGroup = mainPanel.add("group");
    formatGroup.orientation = "row";
    formatGroup.alignChildren = "center";

    formatGroup.add("statictext", undefined, "File Format:");

    var formatItems = ["JPEG (Save for Web)", "JPEG", "PNG (Save for Web)", "PNG"];

    // Create the conditional dropdown options array based on Photoshop version 2022 check/test
    if (parseFloat(app.version) >= 23) {
        formatItems.push("WEBP");
    }

    formatItems.push("PSD", "TIFF");

    var formatDropdown = formatGroup.add("dropdownlist", undefined, formatItems);
    formatDropdown.selection = 0; // default to "JPEG (Save for Web)"

    // Flatten image checkbox - mandatory (and locked) for both JPEG formats, optional for PSD/TIFF/PNG/WEBP
    var flattenCheckbox = formatGroup.add("checkbox", undefined, "Flatten image (required for JPEG)");
    flattenCheckbox.value = true;

    // Row 4: JPEG quality dropdown (0-12, default 9) - shown only for "JPEG"
    var qualityGroup = mainPanel.add("group");
    qualityGroup.orientation = "row";
    qualityGroup.alignChildren = "center";

    qualityGroup.add("statictext", undefined, "JPEG Quality:");

    var qualityItems = [];
    for (var q = 0; q <= 12; q++) {
        qualityItems.push(q.toString());
    }
    var qualityDropdown = qualityGroup.add("dropdownlist", undefined, qualityItems);
    qualityDropdown.selection = 9; // default to "9"

    // Row 5: Quality/compression slider (0-100%, default 75%) - shown for
    // "JPEG (Save for Web)" and "WEBP", which both take a 0-100 quality value.
    var sfwQualityGroup = mainPanel.add("group");
    sfwQualityGroup.orientation = "row";
    sfwQualityGroup.alignChildren = "center";

    sfwQualityGroup.add("statictext", undefined, "Quality:");

    var sfwSlider = sfwQualityGroup.add("slider", undefined, 75, 0, 100);
    sfwSlider.preferredSize.width = 200;

    var sfwValueText = sfwQualityGroup.add("statictext", undefined, "75%");
    sfwValueText.preferredSize.width = 36;

    sfwQualityGroup.visible = false; // hidden until a matching file format is chosen

    function updateFlattenCheckboxState() {
        var format = formatDropdown.selection.text;
        var isJpeg = (format === "JPEG" || format === "JPEG (Save for Web)");
        if (isJpeg) {
            flattenCheckbox.value = true;
            flattenCheckbox.enabled = false;
        } else {
            flattenCheckbox.value = false;
            flattenCheckbox.enabled = true;
        }
    }

    function updateSfwValueText() {
        sfwValueText.text = Math.round(sfwSlider.value) + "%";
    }
    sfwSlider.onChanging = updateSfwValueText; // fires continuously while dragging
    sfwSlider.onChange = updateSfwValueText; // fires on keyboard arrow-key changes

    function getFormatFolderName() {
        var format = formatDropdown.selection.text;
        // Both "JPEG" and "JPEG (Save for Web)" save as .jpg, so they share one folder name.
        if (format === "JPEG (Save for Web)") return "JPEG";
        // Both "PNG" and "PNG (Save for Web)" save as .png, so they share one folder name.
        if (format === "PNG (Save for Web)") return "PNG";
        return format;
    }

    function updateSubfolderCheckboxLabel() {
        subfolderCheckbox.text = "Automatically create \"" + getFormatFolderName() + " Slices\" subfolder";
    }

    function updateFormatOptionsVisibility() {
        var format = formatDropdown.selection.text;
        qualityGroup.visible = (format === "JPEG");
        sfwQualityGroup.visible = (format === "JPEG (Save for Web)" || format === "WEBP");
        updateSubfolderCheckboxLabel();
        updateFlattenCheckboxState();
        updatePathText();
        dlg.layout.layout(true);
        dlg.layout.resize();
    }
    formatDropdown.onChange = updateFormatOptionsVisibility;
    updateFormatOptionsVisibility(); // set correct initial visibility/labels for the default file format

    // Keep track of the raw selected folder (before the optional subfolder is appended)
    var selectedFolder = null;

    function updatePathText() {
        if (!selectedFolder) {
            pathText.text = "No folder selected";
            pathText.helpTip = "";
            return;
        }
        var displayPath = selectedFolder.fullName;
        if (subfolderCheckbox.value) {
            displayPath = displayPath + "/" + getFormatFolderName() + " Slices";
        }
        pathText.text = displayPath;
        pathText.helpTip = displayPath;
    }

    chooseFolderBtn.onClick = function() {
        var folder = Folder.selectDialog("Select output folder for image slices");
        if (folder) {
            selectedFolder = folder;
            updatePathText();
        }
    };

    subfolderCheckbox.onClick = function() {
        updatePathText();
    };

    // Button row - OUTSIDE the main panel/group, right-aligned
    var btnGroup = dlg.add("group");
    btnGroup.orientation = "row";
    btnGroup.alignment = "right";

    var cancelBtn = btnGroup.add("button", undefined, "Cancel", {
        name: "cancel"
    });
    var okBtn = btnGroup.add("button", undefined, "OK", {
        name: "ok"
    });

    var dialogResult = null;

    okBtn.onClick = function() {
        if (!selectedFolder) {
            alert("Please choose an output folder before continuing.");
            return;
        }

        var outputFolder = selectedFolder;
        if (subfolderCheckbox.value) {
            outputFolder = new Folder(selectedFolder.fsName + "/" + getFormatFolderName() + " Slices");
            if (!outputFolder.exists) {
                outputFolder.create();
            }
        }

        var format = formatDropdown.selection.text;
        var quality = null;
        if (format === "JPEG") {
            quality = parseInt(qualityDropdown.selection.text, 10);
        } else if (format === "JPEG (Save for Web)" || format === "WEBP") {
            quality = Math.round(sfwSlider.value);
        }

        dialogResult = {
            folder: outputFolder,
            format: format,
            quality: quality,
            flatten: flattenCheckbox.value
        };
        dlg.close(1);
    };

    cancelBtn.onClick = function() {
        dlg.close(0);
    };

    dlg.defaultElement = okBtn;
    dlg.cancelElement = cancelBtn;

    // On first open, ScriptUI sometimes computes the window's height slightly
    // short (cutting off the OK/Cancel row) before the window has actually been
    // rendered. Forcing another relayout once it's shown fixes that first-open
    // case, matching the correct size seen after any dropdown interaction.
    dlg.onShow = function() {
        dlg.layout.layout(true);
        dlg.layout.resize();
    };

    var shown = dlg.show();
    if (shown === 1) {
        return dialogResult;
    }
    return null;
}
///// SCRIPTUI DIALOG - END /////


///// FUNCTIONS /////

function main() {

    ///// PRE-DIALOG SHOW CHECKS - START /////

    // 1) Check for an open document
    if (app.documents.length === 0) {
        alert("No document is open.\nPlease open a document that contains slices and try again.");
        return;
    }

    // Suppress Photoshop's own dialogs (e.g. "Maximize Compatibility") for the
    // duration of this script, so saving the document never pops up a window.
    var originalDisplayDialogs = app.displayDialogs;
    app.displayDialogs = DialogModes.NO;

    var s2t = stringIDToTypeID,
        AR = ActionReference,
        AD = ActionDescriptor;

    // 2) Check for slices. The document's "slices" list always includes one
    // extra entry for the full-canvas auto slice, so at least one user-defined
    // slice means the list contains more than a single entry.
    var slices;
    try {
        (r = new AR).putProperty(s2t('property'), p = s2t('slices'));
        r.putEnumerated(s2t('document'), s2t('ordinal'), s2t('targetEnum'));
        slices = executeActionGet(r).getObjectValue(p).getList(p);
    } catch (e) {
        app.displayDialogs = originalDisplayDialogs;
        alert("This version of Photoshop does not have access to slices.");
        return;
    }

    if (slices.count <= 1) {
        app.displayDialogs = originalDisplayDialogs;
        alert("No slices were found in this document.\nPlease define slices and try again.");
        return;
    }
    ///// PRE-DIALOG CHECKS - END /////

    var userSettings = showExportDialog();
    if (!userSettings) {
        // User clicked Cancel (or closed the window) - do nothing.
        app.displayDialogs = originalDisplayDialogs;
        return;
    }

    ///// EXPORT - START /////

    app.activeDocument.save(); // Save for later revert

    app.activeDocument.mergeVisibleLayers(); // Merge visible for slice

    if (userSettings.flatten) {
        activeDocument.flatten();
    }

    try {
        try {
            (r = new AR).putProperty(s2t('property'), p = s2t('layerID'));
            r.putEnumerated(s2t('layer'), s2t('ordinal'), s2t('targetEnum'));
            var id = executeActionGet(r).getInteger(p);
        } catch (e) {
            throw "No layer selected!";
        }

        (r = new AR).putProperty(s2t('property'), p = s2t('resolution'));
        r.putEnumerated(s2t('document'), s2t('ordinal'), s2t('targetEnum'));
        var res = executeActionGet(r).getDouble(p);

        (r = new AR).putProperty(s2t('property'), p = s2t('title'));
        r.putEnumerated(s2t('document'), s2t('ordinal'), s2t('targetEnum'));
        var nm = executeActionGet(r).getString(p).replace(/\..+$/, '');

        try {
            (r = new AR).putProperty(s2t('property'), p = s2t('fileReference'));
            r.putEnumerated(s2t('document'), s2t('ordinal'), s2t('targetEnum'));
            var pth = executeActionGet(r).getPath(p);
        } catch (e) {
            throw "File not saved!";
        }

        var outputFolderPath = userSettings.folder.fsName;
        var totalSlices = slices.count - 1; // number of real slices, excluding the auto full-canvas entry

        for (var i = 0; i < slices.count - 1; i++) {
            (r = new AR).putIdentifier(s2t('layer'), id);
            (d = new AD).putReference(s2t('target'), r);
            executeAction(s2t('select'), d, DialogModes.NO);

            (r = new AR).putProperty(s2t('channel'), s2t('selection'));
            (d = new AD).putReference(s2t('target'), r);
            d.putObject(s2t('to'), s2t('rectangle'),
                function(b, d) {
                    for (var i = 0; i < b.count; i++)
                        d.putUnitDouble(k = (b.getKey(i)), s2t('pixelsUnit'), b.getInteger(k))
                    return d;
                }(slices.getObjectValue(i).getObjectValue(s2t('bounds')), new AD)
            );
            executeAction(s2t('set'), d, DialogModes.NO);

            try {
                (d = new AD).putString(s2t("copyHint"), "pixels");
                executeAction(s2t("copyEvent"), d, DialogModes.NO);

                (d = new AD).putClass(s2t("mode"), s2t("RGBColorMode"));
                d.putUnitDouble(s2t("width"), s2t("distanceUnit"), 1 * 72 / res);
                d.putUnitDouble(s2t("height"), s2t("distanceUnit"), 1 * 72 / res);
                d.putUnitDouble(s2t("resolution"), s2t("densityUnit"), res);
                d.putEnumerated(s2t("fill"), s2t("fill"), s2t("white"));
                d.putInteger(s2t("depth"), 8);
                d.putString(s2t("profile"), "sRGB IEC61966-2.1");
                (d1 = new AD).putObject(s2t("new"), s2t("document"), d);
                executeAction(s2t("make"), d1, DialogModes.NO);

                (d = new AD).putEnumerated(s2t("antiAlias"), s2t("antiAliasType"), s2t("antiAliasNone"));
                d.putClass(s2t("as"), s2t("pixel"));
                executeAction(s2t("paste"), d, DialogModes.NO);

                executeAction(s2t("revealAll"), new AD, DialogModes.NO);
                if (userSettings.flatten) {
                    executeAction(s2t("flattenImage"), undefined, DialogModes.NO);
                }

                var sliceNumber = totalSlices - i; // reversed: first slice gets the highest number
                var extension = (userSettings.format === "PSD") ? ".psd" :
                    (userSettings.format === "TIFF") ? ".tif" :
                    (userSettings.format === "PNG" || userSettings.format === "PNG (Save for Web)") ? ".png" :
                    (userSettings.format === "WEBP") ? ".webp" : ".jpg";
                var outFile = File(outputFolderPath + '/' + nm + '-' + ('0' + sliceNumber).slice(-2) + extension);

                switch (userSettings.format) {
                    case "JPEG (Save for Web)":
                        // Quality (0-100) from the dialog slider
                        exportJPEG(outFile, userSettings.quality);
                        // Photoshop's Save for Web engine keeps internal state between
                        // calls and will silently do nothing on the 2nd+ call within a
                        // single script run unless its caches are purged in between.
                        app.purge(PurgeTarget.ALLCACHES);
                        break;

                    case "PSD":
                        // saveLayers: keep layers when the user did not request flatten
                        savePSD(outFile, !userSettings.flatten);
                        break;

                    case "TIFF":
                        saveTIFF(outFile, !userSettings.flatten);
                        break;

                    case "PNG":
                        savePNG(outFile);
                        break;

                    case "PNG (Save for Web)":
                        exportPNG(outFile);
                        // Same Save for Web caching quirk as the JPEG (Save for Web)
                        // case above - purge so the next call actually exports.
                        app.purge(PurgeTarget.ALLCACHES);
                        break;

                    case "WEBP":
                        saveWebP(outFile, userSettings.quality); // requires Photoshop 23.2 / 2022 or later
                        break;

                    default: // "JPEG"
                        // Quality (0-12) from the dialog dropdown
                        saveJPEG(outFile, userSettings.quality);
                        break;
                }

                executeAction(s2t("close"), new AD, DialogModes.NO);

                (r = new AR).putProperty(s2t('channel'), s2t('selection'));
                (d = new AD).putReference(s2t('null'), r);
                d.putEnumerated(s2t('to'), s2t('ordinal'), s2t('none'));
                executeAction(s2t('set'), d, DialogModes.NO);
            } catch (e) {
                // Log the failure for this slice but keep going, so one bad
                // slice doesn't silently abort every slice after it.
                $.writeln("Export Slices to JPEG - Error on slice " + (totalSlices - i) + ": " + e);
                // Clean up a stray temp document if one was left open.
                try {
                    if (app.documents.length > 1) {
                        activeDocument.close(SaveOptions.DONOTSAVECHANGES);
                    }
                } catch (cleanupError) {}
            }
        }
    } catch (e) {
        // No dialogs after OK is pressed - log any error to the ExtendScript
        // console instead of alerting, so the export stays silent.
        $.writeln("Export Slices to JPEG - Error: " + e);
    }

    executeAction(stringIDToTypeID("revert"), undefined, DialogModes.NO);

    // Deselect any active selection so the document is left in a clean state.
    try {
        activeDocument.selection.deselect();
    } catch (e) {}

    app.displayDialogs = originalDisplayDialogs;
    ///// EXPORT - END /////
}

function saveWebP(file, quality) {
    /*
    Adapted from v1.1 - 12th March 2023, Stephen Marsh
    https://community.adobe.com/t5/photoshop-ecosystem-discussions/saving-webp-image-by-script/td-p/13642577
    Preferences (compression type, metadata, save-as-copy) are set at the top of the script.
    Quality (0-100) is taken from the dialog slider when using lossy compression.
    */
    function s2t(s) {
        return app.stringIDToTypeID(s);
    }
    var descriptor = new ActionDescriptor();
    var descriptor2 = new ActionDescriptor();

    // Compression parameters = "compressionLossless" | "compressionLossy"
    descriptor2.putEnumerated(s2t("compression"), s2t("WebPCompression"), s2t(webpCompressionType));
    if (webpCompressionType === "compressionLossy") {
        // 0 (lowest lossy quality) - 100 (highest lossy quality)
        descriptor2.putInteger(s2t("quality"), quality);
    }

    // Metadata options (from preferences at top of script)
    descriptor2.putBoolean(s2t("includeXMPData"), webpIncludeXMPData);
    descriptor2.putBoolean(s2t("includeEXIFData"), webpIncludeEXIFData);
    descriptor2.putBoolean(s2t("includePsExtras"), webpIncludePsExtras);

    // WebP format and save path
    descriptor.putObject(s2t("as"), s2t("WebPFormat"), descriptor2);
    descriptor.putPath(s2t("in"), file);

    // Save As = false | Save As a Copy = true
    descriptor.putBoolean(s2t("copy"), webpSaveAsCopy);

    // Lowercase extension
    descriptor.putBoolean(s2t("lowerCase"), true);

    // Execute the save
    executeAction(s2t("save"), descriptor, DialogModes.NO);
}

function savePSD(savePSDFile, savePSDLayers) {
    var psdSaveOptions = new PhotoshopSaveOptions();
    psdSaveOptions.embedColorProfile = embedColorProfile;
    psdSaveOptions.alphaChannels = alphaChannels;
    psdSaveOptions.layers = savePSDLayers;
    psdSaveOptions.annotations = annotations;
    psdSaveOptions.spotColors = spotColors;
    app.activeDocument.saveAs(savePSDFile, psdSaveOptions, true, Extension.LOWERCASE);
}

function saveTIFF(saveTIFFFile, saveTIFFLayers) {
    var tiffSaveOptions = new TiffSaveOptions();
    tiffSaveOptions.embedColorProfile = tiffEmbedColorProfile;
    tiffSaveOptions.byteOrder = tiffByteOrder;
    tiffSaveOptions.transparency = tiffTransparency;
    tiffSaveOptions.layers = saveTIFFLayers;
    tiffSaveOptions.layerCompression = tiffLayerCompression;
    tiffSaveOptions.interleaveChannels = tiffInterleaveChannels;
    tiffSaveOptions.alphaChannels = tiffAlphaChannels;
    tiffSaveOptions.annotations = tiffAnnotations;
    tiffSaveOptions.spotColors = tiffSpotColors;
    tiffSaveOptions.saveImagePyramid = tiffSaveImagePyramid;
    tiffSaveOptions.imageCompression = tiffImageCompression;
    app.activeDocument.saveAs(saveTIFFFile, tiffSaveOptions, true, Extension.LOWERCASE);
}

function saveJPEG(saveFileJPEG, quality) {
    var jpgSaveOptions = new JPEGSaveOptions();
    jpgSaveOptions.embedColorProfile = jpegEmbedColorProfile;
    jpgSaveOptions.formatOptions = jpegFormatOptions;
    jpgSaveOptions.matte = jpegMatte;
    // Prefer quality from the dialog (0-12); fall back to preference default
    jpgSaveOptions.quality = (typeof quality === "number") ? quality : jpegQuality;
    app.activeDocument.saveAs(saveFileJPEG, jpgSaveOptions, true, Extension.LOWERCASE);
}

function exportJPEG(exportFileJPEG, quality) {
    var sfwOptions = new ExportOptionsSaveForWeb();
    sfwOptions.format = SaveDocumentType.JPEG;
    sfwOptions.includeProfile = sfwIncludeProfile;
    sfwOptions.interlaced = sfwInterlaced;
    sfwOptions.optimized = sfwOptimized;
    // Prefer quality from the dialog (0-100); fall back to preference default
    sfwOptions.quality = (typeof quality === "number") ? quality : sfwQuality;
    app.activeDocument.exportDocument(exportFileJPEG, ExportType.SAVEFORWEB, sfwOptions);
}

function savePNG(savePNGFile) {
    var pngOptions = new PNGSaveOptions();
    pngOptions.compression = pngCompression;
    pngOptions.interlaced = pngInterlaced;
    app.activeDocument.saveAs(savePNGFile, pngOptions, true, Extension.LOWERCASE);
}

function exportPNG(exportFilePNG) {
    var pngOptions = new ExportOptionsSaveForWeb();
    pngOptions.PNG8 = pngSfwPNG8;
    pngOptions.transparency = pngSfwTransparency;
    pngOptions.interlaced = pngSfwInterlaced;
    pngOptions.quality = pngSfwQuality;
    pngOptions.includeProfile = pngSfwIncludeProfile;
    pngOptions.format = SaveDocumentType.PNG;
    app.activeDocument.exportDocument(exportFilePNG, ExportType.SAVEFORWEB, pngOptions);
}

1. Copy the code text to the clipboard
2. Open a new blank file in a plain-text editor (not in a word processor)
3. Paste the code in
4. Save as a plain text format file – .txt
5. Rename the saved file extension from .txt to .jsx
6. Install or browse to the .jsx file to run (see below)

https://prepression.blogspot.com/2017/11/downloading-and-installing-adobe-scripts.html

​@s15199d 

I read the solutions at the link and don’t know why they didn’t work for you.

EDIT: Take a look at the following animated GIF, it may not be obvious how the current slice settings are displayed vs. the last used format:

Although not a direct answer, an alternative is to use a script to save all slices to JPEG.

/* 
https://community.adobe.com/t5/photoshop-ecosystem-discussions/can-slices-be-saved-at-300-ppi-in-photoshop/m-p/14272292
v1.0 - 2nd December 2023, Stephen Marsh
Based on a script from jazz-y
https://community.adobe.com/t5/photoshop-ecosystem-discussions/script-for-splitting-multiple-psds-to-defined-slices/m-p/12592481
https://community.adobe.com/t5/photoshop-ecosystem-discussions/divide-my-image-to-layers/m-p/12467520
*/

#target photoshop

///// ADDITION TO ORIGINAL CODE - START /////
activeDocument.save();
activeDocument.flatten();
///// ADDITION TO ORIGINAL CODE - END /////

var s2t = stringIDToTypeID,
    AR = ActionReference,
    AD = ActionDescriptor;

try {
    try {
        (r = new AR).putProperty(s2t('property'), p = s2t('layerID'));
        r.putEnumerated(s2t('layer'), s2t('ordinal'), s2t('targetEnum'));
        var id = executeActionGet(r).getInteger(p);
    } catch (e) {
        throw "No layer selected!\nOpen the document and select layer"
    }

    try {
        (r = new AR).putProperty(s2t('property'), p = s2t('slices'));
        r.putEnumerated(s2t('document'), s2t('ordinal'), s2t('targetEnum'));
        var slices = executeActionGet(r).getObjectValue(p).getList(p);
    } catch (e) {
        throw "This version of photoshop does not have access to slices"
    }

    (r = new AR).putProperty(s2t('property'), p = s2t('resolution'));
    r.putEnumerated(s2t('document'), s2t('ordinal'), s2t('targetEnum'));
    var res = executeActionGet(r).getDouble(p);

    (r = new AR).putProperty(s2t('property'), p = s2t('title'));
    r.putEnumerated(s2t('document'), s2t('ordinal'), s2t('targetEnum'));
    var nm = executeActionGet(r).getString(p).replace(/\..+$/, '');

    try {
        (r = new AR).putProperty(s2t('property'), p = s2t('fileReference'));
        r.putEnumerated(s2t('document'), s2t('ordinal'), s2t('targetEnum'));
        var pth = executeActionGet(r).getPath(p);
    } catch (e) {
        throw "File not saved!"
    }

    for (var i = 0; i < slices.count - 1; i++) {
        (r = new AR).putIdentifier(s2t('layer'), id);
        (d = new AD).putReference(s2t('target'), r);
        executeAction(s2t('select'), d, DialogModes.NO);

        (r = new AR).putProperty(s2t('channel'), s2t('selection'));
        (d = new AD).putReference(s2t('target'), r);
        d.putObject(s2t('to'), s2t('rectangle'),
            function (b, d) {
                for (var i = 0; i < b.count; i++)
                    d.putUnitDouble(k = (b.getKey(i)), s2t('pixelsUnit'), b.getInteger(k))
                return d;
            }(slices.getObjectValue(i).getObjectValue(s2t('bounds')), new AD)
        );
        executeAction(s2t('set'), d, DialogModes.NO);

        try {
            (d = new AD).putString(s2t("copyHint"), "pixels");
            executeAction(s2t("copyEvent"), d, DialogModes.NO);

            (d = new AD).putClass(s2t("mode"), s2t("RGBColorMode"));
            d.putUnitDouble(s2t("width"), s2t("distanceUnit"), 1 * 72 / res);
            d.putUnitDouble(s2t("height"), s2t("distanceUnit"), 1 * 72 / res);
            d.putUnitDouble(s2t("resolution"), s2t("densityUnit"), res);
            d.putEnumerated(s2t("fill"), s2t("fill"), s2t("white"));
            d.putInteger(s2t("depth"), 8);
            d.putString(s2t("profile"), "sRGB IEC61966-2.1");
            (d1 = new AD).putObject(s2t("new"), s2t("document"), d);
            executeAction(s2t("make"), d1, DialogModes.NO);

            (d = new AD).putEnumerated(s2t("antiAlias"), s2t("antiAliasType"), s2t("antiAliasNone"));
            d.putClass(s2t("as"), s2t("pixel"));
            executeAction(s2t("paste"), d, DialogModes.NO);

            executeAction(s2t("revealAll"), new AD, DialogModes.NO);
            executeAction(s2t("flattenImage"), undefined, DialogModes.NO);

            ///// ADDITION TO ORIGINAL CODE - START /////
            var actDesc = new ActionDescriptor();
            var idextendedQuality = stringIDToTypeID("extendedQuality");
            actDesc.putInteger(idextendedQuality, 12); // 0-12
            (d = new AD).putObject(s2t("as"), s2t("JPEG"), actDesc, new AD);
            d.putPath(s2t("in"), File(pth.path + '/' + nm + ' ' + ('0' + i).slice(-2) + '.jpg'));
            d.putEnumerated(s2t("saveStage"), s2t("saveStageType"), s2t("saveBegin"));
            executeAction(s2t("save"), d, DialogModes.NO);
            ///// ADDITION TO ORIGINAL CODE - END /////            

            executeAction(s2t("close"), new AD, DialogModes.NO);

            (r = new AR).putProperty(s2t('channel'), s2t('selection'));
            (d = new AD).putReference(s2t('null'), r);
            d.putEnumerated(s2t('to'), s2t('ordinal'), s2t('none'));
            executeAction(s2t('set'), d, DialogModes.NO);
        } catch (e) {
            throw e + "\nScript cannot create layer from empty space!\nMake sure that current layer contains pixels in all slices."
        }
    }
} catch (e) {
    alert(e)
}


///// ADDITION TO ORIGINAL CODE - START /////
executeAction(stringIDToTypeID("revert"), undefined, DialogModes.NO);
///// ADDITION TO ORIGINAL CODE - END /////

1. Copy the code text to the clipboard
2. Open a new blank file in a plain-text editor (not in a word processor)
3. Paste the code in
4. Save as a plain text format file – .txt
5. Rename the saved file extension from .txt to .jsx
6. Install or browse to the .jsx file to run (see below)

https://prepression.blogspot.com/2017/11/downloading-and-installing-adobe-scripts.html