Why does the data event trigger multiple times until the server reads the contents of the response?

  node.js, question

var data = “”;
res.on(‘data’, function (chunk) {
Dataplus = chunk;
}) .on(“end”, function () {

});
If I don’t write this event monitor, will nodejs or emit this data event many times? I don’t understand the calling process of this event very well, and I want to seek popular science.

Because he wants to set a fixed memory length to receive messages, not all messages are received at one time, but all messages need to be received multiple times.