Export InDesign pages to individual files with custom file name.

ExportPages.jsx

/**
 * Export InDesign pages to individual files with custom file name.
 * 
 * References:
 * 
 *      https://www.indesignjs.de/extendscriptAPI/indesign-latest/index.html#ExportFormat.html
 *      https://github.com/ExtendScript/wiki/wiki
 * 
 * License: MIT
 */

// Start with the source document open
var sourceDoc = app.activeDocument;

// Get the item names
var names = [];
var items = sourceDoc.pages[1].allPageItems;
for (n = 0; n < items.length; n++) {
    if (items[n].name !== '') {
        names.push(items[n].name);
    }
}
// Reverse to get the same order as the source document
names.reverse();

// Select the target folder
var targetFolder = Folder.selectDialog("Select a folder");
if (targetFolder != null && targetFolder instanceof Folder) {
    targetFolder = targetFolder.fsName + "/";
} else {
    alert('Invalid target folder.');
    targetFolder = null;
}

if (targetFolder != null) {
    for (p = 0; p < sourceDoc.pages.length; p++) {
        var page = sourceDoc.pages[p];
        var newDoc = app.open(targetFolder + 'clean.indd', false);

        for (i = 0; i < names.length; i++) {
            var item = page.pageItems.itemByName(names[i]);
            if (item.isValid) {
                item.duplicate(newDoc.activeLayer);
            }
        }

        var frame = newDoc.activeLayer.textFrames.itemByName("output_filename");

        // Trigger output format by file name
        var fileName = targetFolder + frame.contents;
        if (fileName.indexOf('.png') !== -1) {
            newDoc.exportFile(ExportFormat.PNG_FORMAT, fileName);
        } else {
            if (fileName.indexOf('.jpg') === -1) {
                fileName = fileName + '.jpg';
            }

            newDoc.exportFile(ExportFormat.JPG, fileName);
        }

        newDoc.close(SaveOptions.NO);
    }

    alert('Finished exporting pages.');
} else {
    alert('Invalid target destination.')
}