AppleScript - Executing JavaScript in Safari and Chrome

I haven't used AppleScript much, but I was recently working on a script to automate a workflow and I was surprised to discover that each browser uses different commands to execute JavaScript.

Specifically, Safari uses do JavaScript "add code here" in document X and Chrome requires execute javascript "add code here"

Here's an example of each:

Safari

tell application "Safari"
	open location "https://google.com"
	if (do JavaScript "document.readyState" in document 1) is "complete" then set pageLoaded to true
	display dialog pageLoaded as string
end tell

Google

tell application "Google Chrome"
     open location "https://google.com"
     if (execute javascript "document.readyState") is "complete" then set pageLoaded to true
     display dialog pageLoaded as string
end tell

A couple notes:

- AppleScript.app autocorrects the second example to a lowercase JavaScript, but either should work.

- Safari requires that a document is specified

- If you're using Firefox, it's currently not possible to execute JavaScript with AppleScript