Nested Repeat Loops in Applescript

Question

The following code has two lists: myURLs and myIMGs. I want to loop through the sites listed in myURLs, take a screenshot, then save them in my Shared folder as the file name listed in myIMGs. So, google.com's image will be saved as "google.jpg", and so forth. The list in myIMGs corresponds to the list in myURLs.
This is what I have, but it doesn't quite work. It loads the first URL from myURLs, takes a screenshot of it, but then loops through each file name in myIMGs and saves that one screenshot with all those various file names. Then, it loads the next URL in myURLs and does the same thing. How do I set the file names in the myIMGs list to correspond to the URLs being loaded from myURLs? I'm having trouble with the nested loops.
set myURLs to {"https://google.com", "https://wikipedia.org", "https://bing.com", "https://apple.com"}
set myIMGs to {"google.jpg", "wikipedia.jpg", "bing.jpg", "apple.jpg"}
-- Sets settings of Safari without interferring with user's settings.
repeat with myURL in myURLs
          tell application "Safari"
                    set myDoc to front document
                    set windowID to id of window 1
                    do JavaScript ("window.open('" & myURL & "','_blank','titlebar=0');") in document 1
  close window id windowID
                    set the bounds of the front window to {0, 20, 915, 812}
  delay 5
          end tell
-- Screengrab, crop and save to Shared folder
          repeat with myIMG in myIMGs
                    do shell script "screencapture -o -l$(osascript -e 'tell app \"Safari\" to id of window 1') /Users/Shared/" & myIMG
                    set this_file to "Macintosh HD:Users:Shared:" & myIMG
                    try
                              tell application "Image Events"
  -- start the Image Events application
  launch
  -- open the image file
                                        set this_image to open this_file
  -- get dimensions of the image
                                        copy dimensions of this_image to {W, H}
  -- Crops off the Safari header
  crop this_image to dimensions {W, H - 50}
  -- save the changes
                                        save this_image with icon
  -- purge the open image data
  close this_image
                              end tell
                    end try
          end repeat
end repeat

Answer 1

Switch to an indexed loop and you don't need the extra repeat loop; you can run the two lists in parallel. See my changes in red:
set myURLs to {"https://google.com", "https://wikipedia.org", "https://bing.com", "https://apple.com"}
set myIMGs to {"google.jpg", "wikipedia.jpg", "bing.jpg", "apple.jpg"}
-- Sets settings of Safari without interferring with user's settings.
repeat with i from 1 to (count of myURLs)
          tell application "Safari"
                    set myDoc to front document
                    set windowID to id of window 1
                    do JavaScript ("window.open('" & item i of myURLs & "','_blank','titlebar=0');") in document 1
                              close window id windowID
                    set the bounds of the front window to {0, 20, 915, 812}
                              delay 5
          end tell
  -- Screengrab, crop and save to Shared folder
          do shell script "screencapture -o -l$(osascript -e 'tell app \"Safari\" to id of window 1') /Users/Shared/" & (item i of myIMGs)
          set this_file to "Macintosh HD:Users:Shared:" & myIMG
          try
                    tell application "Image Events"
  -- start the Image Events application
                              launch
  -- open the image file
                              set this_image to open this_file
  -- get dimensions of the image
                              copy dimensions of this_image to {W, H}
  -- Crops off the Safari header
                              crop this_image to dimensions {W, H - 50}
  -- save the changes
                              save this_image with icon
  -- purge the open image data
                              close this_image
                    end tell
          end try
end repeat