Ensure you are running webui with the API enabled (--api in your webui-user.bat)
Saves files to a folder called output in the working directory
You can specify a filename per entry (see example 'hello') or uses {time} {prompt} {seed} formatting if not specified
Script, save as file2prompt.mjs or something
Create config.json next to the mjs file, example:
Run with node file2prompt.mjs
API txt2img schema: