From the wiki article:
- Demo Using KM Custom HTML Prompt with AppleScript & JXA
- If the user closes the prompt/form by clicking the OK button or otherwise submitting the form, then the data on the form is saved back to the corresponding Keyboard Maestro Variable
To set initial values, set the KM variables before you execute the Action, and then the KM variables are updated with the user's changes when the user clicks OK.