Difference between response.setHeader and response.writeHead?

Question

In my application, I have my Nodejs server send a JSON response. I found two ways to do this but I'm not sure what the differences are.

One way is

var json = JSON.stringify(result.rows); response.writeHead(200, {'content-type':'application/json', 'content-length':Buffer.byteLength(json)});  response.end(json); 

And my other way is

var json = JSON.stringify(result.rows); response.setHeader('Content-Type', 'application/json'); response.end(json); 

Both ways work and I'm just wondering what the difference is between the two and when I should use one over the other.

Answer 1

response.setHeader() allows you only to set a singular header.

response.writeHead() will allow you to set pretty much everything about the response head including status code, content, and multiple headers.

Consider the NodeJS docs:

response.setHeader(name, value)

Sets a single header value for implicit headers. If this header already exists in the to-be-sent headers, its value will be replaced. Use an array of strings here to send multiple headers with the same name.

var body = "hello world"; response.setHeader("Content-Length", body.length); response.setHeader("Content-Type", "text/plain"); response.setHeader("Set-Cookie", "type=ninja"); response.status(200); 

response.writeHead(statusCode[, statusMessage][, headers]))

Sends a response header to the request. The status code is a 3-digit HTTP status code, like 404. The last argument, headers, are the response headers. Optionally one can give a human-readable statusMessage as the second argument.

var body = "hello world"; response.writeHead(200, {     "Content-Length": body.length,     "Content-Type": "text/plain",     "Set-Cookie": "type=ninja" });