Add some lines for the selected layers

Line 1 sets the variable to the original/parent/containing layered file:

var currentDoc = app.activeDocument;

Then line 14 redefines the variable again, this time to the opened smart object document.

Then the JPEG is saved into the folder using the path of the variable of the smart object document, which is a buried temp folder if the SO is embedded.

So changing line 1 to:

var parentDoc = app.activeDocument;

Then line 15 to:

var docpath = parentDoc.path;

Will at least save the JPEG file to the parent PSD file location, rather than the temporary directory for the smart object PSB file.

So before trying to make this work for multiple selected layers, it needs to work for a single selected layer. But perhaps I misunderstood your intent.

P.S. Do you really wish to have files named such as "503       172.jpg" with 7 word spaces?

This example was when I had my rulers set to pixels, but when changing the rulers to CM I get "6       2.jpg". Rather than presuming the unit of measure, it is best to explicitly set it in the script:

https://gist.github.com/MarshySwamp/898ae3237305787d0683125166aeb480

@Stephen Marsh 

I also tried the second code, but it only works on one layer, with a message showing that there is a problem with the layers

I don't know where the problem is

if (app.documents.length > 0) {
    var myDocument = app.activeDocument;
    myDocument.suspendHistory("Undo script...", "main(myDocument)");
}

function main() {
    var theLayers = getSelectedLayersIdx();
    for (var p = 0; p < theLayers.length; p++) {
        selectLayerByIndex(theLayers[p], false);

        // Your code here
        if (activeDocument.activeLayer.kind == "LayerKind.SMARTOBJECT") {
    runMenuItem(stringIDToTypeID('placedLayerEditContents'))
  
} else {
    app.runMenuItem(stringIDToTypeID('newPlacedLayer'));
    runMenuItem(stringIDToTypeID('placedLayerEditContents'));

}
       }
}


///// Functions /////

function selectLayerByIndex(index, add) {
    add = undefined ? add = false : add
    var ref = new ActionReference();
    ref.putIndex(charIDToTypeID("Lyr "), index);
    var desc = new ActionDescriptor();
    desc.putReference(charIDToTypeID("null"), ref);
    if (add) desc.putEnumerated(stringIDToTypeID("selectionModifier"), stringIDToTypeID("selectionModifierType"), stringIDToTypeID("addToSelection"));
    desc.putBoolean(charIDToTypeID("MkVs"), false);
    try {
        executeAction(charIDToTypeID("slct"), desc, DialogModes.NO);
    } catch (e) {
        alert(e.message);
    }
}

// by paul mr
function getSelectedLayersIdx() {
    var selectedLayers = new Array;
    var ref = new ActionReference();
    ref.putEnumerated(charIDToTypeID("Dcmn"), charIDToTypeID("Ordn"), charIDToTypeID("Trgt"));
    var desc = executeActionGet(ref);
    if (desc.hasKey(stringIDToTypeID('targetLayers'))) {
        desc = desc.getList(stringIDToTypeID('targetLayers'));
        var c = desc.count
        var selectedLayers = new Array();
        for (var i = 0; i < c; i++) {
            try {
                activeDocument.backgroundLayer;
                selectedLayers.push(desc.getReference(i).getIndex());
            } catch (e) {
                selectedLayers.push(desc.getReference(i).getIndex() + 1);
            }
        }
    } else {
        var ref = new ActionReference();
        ref.putProperty(charIDToTypeID("Prpr"), charIDToTypeID("ItmI"));
        ref.putEnumerated(charIDToTypeID("Lyr "), charIDToTypeID("Ordn"), charIDToTypeID("Trgt"));
        try {
            activeDocument.backgroundLayer;
            selectedLayers.push(executeActionGet(ref).getInteger(charIDToTypeID("ItmI")) - 1);
        } catch (e) {
            selectedLayers.push(executeActionGet(ref).getInteger(charIDToTypeID("ItmI")));
        }
    }
    return selectedLayers;
}