Question: I'm curious if AppleScript can access each specific tab in a browser and execute some javascript in them. 

Anyone have ideas?

Answer: 
The function below runs JavaScript in each tab of the frontmost window in Chrome and concatenates the output. To run JavaScript in in all windows, replace `window 1` with `windows`.

```none
xjss(){ osascript -e'on run {a}
    set o to ""
    tell app "Google Chrome" to repeat with t in (get tabs of window 1)
        tell t to set o to o & (execute JavaScript a) & linefeed
    end
end' -- "$1"; }

```

This runs JavaScript in only the frontmost tab:

```none
xjs(){ osascript -e'on run {a}
    tell app "Google Chrome" to tell active tab of window 1 to execute JavaScript a
end' -- "$1"; }

```

Here are similar functions for Safari:

```none
sjss(){ osascript -e'on run {a}
    set o to ""
    tell app "Safari" to repeat with t in (get tabs of window 1)
        tell t to set o to o & (do JavaScript a) & linefeed
    end
end' -- "$1"; }

sjs(){ osascript -e'on run {a}
    tell app "Safari" to tell document 1 to do JavaScript a
end' -- "$1"; }

```

Since some version of Chrome released in 2018, an error like this is shown by default when running an `execute JavaScript` command:

> 
> 78:98: execution error: Google Chrome got an error: Executing JavaScript through AppleScript is turned off. To turn it on, from the menu bar, go to View > Developer > Allow JavaScript from Apple Events. For more information: <https://support.google.com/chrome/?p=applescript> (12)
> 
> 
> 

Safari has a similar preference in "Develop > Allow JavaScript from Apple Events" which was turned off by default in macOS version 10.11.5 (released in 2016-05-16).
Recently Google Chrome disabled the ability to execute JavaScript via AppleScript. I'm having trouble finding a reference link, but in Chrome Canary v59 it doesn't work and gives a message saying it's disabled, and I'm seeing it still work in Chrome v57 so it's got to be very new.