icsio is an API for modifing calendar subscriptions.
To perform a basic ICS modification, provide the API with a target calendar URL, encoded using encodeURIComponent:
encodeURIComponent("https://example.com") // https%3A%2F%2Fexample.comPass this as the url query parameter. You can then supply one or more pairs of rin and rout query parameters to define a regular expression to match and the text to replace it with. Both values must also be encoded.
GET http://localhost:3000?url=https%3A%2F%2Fexample.com&rin=%28%3Fm%29%5ESUMMARY%3A%5CS%2B%20&rout=SUMMARY%3A