multiple layers export script in jpg

T shirt change 

I believe that these are the droids you are looking for:

https://github.com/mechanicious/photoshopCompositionComposer

There is no shortage of T-shirt Mockup Templates on  WWW T-shirt Mockup 

With a mockup template its easy to place Logo on a T-Shirt. It would also be easy to change the T-Shirts Color, Fabric, texture etc. However, replacing the T-Shirt would make everything complicated and not easy to do.  For T-Shirt are all not the same.  They come in may styles and sizes.  So where logo can be placed will differ from t-shirt to t-shirt. Where Fabrics will be cut and placed into the t-shirt will change from t-shirt to t-shirt.  T-Shirt templates I have seen that can be automatically populated with Photoshop automation  seem to be for  a fixed  T-shirts where component of the T-Shirt are changed with different design elements.   If there are different T-shirt they would all be in the template and elements would be changes on each or there would be a template for each T-shirt design. Some Template have multiple views of a T-shirt like a front and back view.   I have not seen a template where different designed T-shirts are place on a model and Logo applied to the populated T-Shirt.

A mockup template may be very simple like this one the has two smart object layer that have their object repopulated.

That is populated by running a script that you point to the mockups, to the replacements and to the output folder through the script dialog  that may also have other populating options. Smart Object can be populated with different methods.  Replace Content requires all replacements to be exactly the same Size Aspect ratio and print resolution as the object in the template.  Where any size replacement can be edited into the existing object.

The Script will open the mockup templates and populate them and close them, When processing is done nothing will be open in Photoshop. The script will putout a notification as to how many mockup templates it populated and how mat designs were populated into the mockup templates and how long the process took.

The output folder will contain the jpeg files the script save from the populated mockup templates.

It can be Scripted in JavaScript. 

It can be done with two for-clauses (with their numbers of iterations depending on the number of Layers in the two Folders). 

Saving and naming jpgs is also not a problem. 

Do you have any JavaScript-knowledge?