Thank you for the example shown.
https://github.com/imagetyperz-api/imagetyperz-api-nodejs/blob/master/examples/geetestV4.js

But can you tell me what to do next with "response"?

Just because I make a request, the captcha does not disappear from the page. Just sending GET request with received data will not work. How do I get the value of "w" and "callback"?