Scripting in Photoshop is used to automate repetitive tasks and are often used as a creative tool to streamline tasks that might be too time consuming to do manually. For example, you could write a script to generate a number of localized versions of a particular image or to gather information about the various color profiles used by a collection of images.
Photoshop can be scripted through COM(Component Object Model). Its DOM(Document Object Model) is the same when accessing it through either its own JavaScript engine or Python or any other scripting language it supports. The Photoshop DOM consists of a hierarchical representation of the Photoshop application, the documents used in it, and the components of the documents. The DOM allows you to programmatically access and manipulate the document and its components. For example, through the DOM, you can create a new document, add a layer to an existing document, or change the background color of a layer. Most of the functionality available through the Photoshop user interface is available through the DOM.
Photoshop scripting officially supports JavaScript, AppleScript & VBScript. However, Scripting in Python is also fairly easy if not easier if you're already comfortable with Python. You may have already heard that Python is gaining in popularity, but did you know it’s now the most popular introductory programming language in U.S. universities? Python is also cross platform just like JavaScript is and lately becoming one of the fastest growing programming language according to StackOverflow as of September 2017
Python is easy to use, powerful, and versatile, making it a great choice for beginners and experts alike. Python’s readability makes it a great first programming language - it allows you to think like a programmer and not waste time understanding the mysterious syntax that other programming languages can require.
Python allows you to access COM and it's DOM with the help of a Python extensions like "pypiwin32" or "comtypes". Install these modules and you're ready to start scripting Photoshop in Python
pip install pypiwin32orpip install comtypes
from win32com.client import Dispatch
app = Dispatch("Photoshop.Application")
doc = app.Documents.Add(320, 240)
layerRef = doc.ArtLayers.Add()
psTextLayer = 2 # from enum PsLayerKind
layerRef.Kind = psTextLayer
textItem = layerRef.TextItem
textItem.Contents = "HELLO WORLD!"
textItem.Position = (120, 120)There's not a straight forward way, you need to read the documentation to understand what properties/attributes are available for a scripting object, or possibly a COM browser. For example, I've extracted the Python scripting object reference for Photoshop CC 2018 at doc_reference
See gui_tool for an example of how you can use Photoshop Scripting to develop your own tool/utilities
Yes, scripting on Mac is also possible, see mac_scripting for more details