Javascript – http get NodeJS how to get error status code

httpjavascriptnode.js

OK, I must be dense since I cannot find anywhere how to get the error status codes when using Node.JS http.get or http.request.

My code:

var deferred = $q.defer();
var req = https.get(options, function(response) {
  var str = '';
  response.on('data', function(chunk) {
    str += chunk;
  });
  response.on('end', function() {
    console.log("[evfService] Got user info: " + str);
    deferred.resolve(str);
  });
});

req.on('error', function(e) {
  deferred.reject(e);
});

In that "req.on" bit, what I want is the http status code (i.e. 401, 403, etc.). What I get is a semi-useless error object that does not give me the code or any reference to the response object.

I have tried intercepting in the function(response) callback, but when there is a 404, it never gets called.

Thanks!

Best Answer

Your callback gets called regardless of the response status code from the server, so within your callback, check response.statusCode. That is, a 4xx status code isn't an error at the level you're working at; the server responded, it's just that the server responded by saying the resource wasn't available (etc.)

This is in the documentation but characteristically vague. Here's the example they give, with a comment pointing to the relevant bit:

var https = require('https');

https.get('https://encrypted.google.com/', function(res) {
  console.log("statusCode: ", res.statusCode); // <======= Here's the status code
  console.log("headers: ", res.headers);

  res.on('data', function(d) {
    process.stdout.write(d);
  });

}).on('error', function(e) {
  console.error(e);
});

If you try that with (say) an unknown resource, you'll see statusCode: 404.

So for what you're doing, you may want something like this:

var deferred = $q.defer();

var req = https.get(options, function (response) {
    var str = "";

    if (response.statusCode < 200 || response.statusCode > 299) { // (I don"t know if the 3xx responses come here, if so you"ll want to handle them appropriately
        response.on("data", function() { } ); // ¹
        deferred.reject(/*...with appropriate information, including statusCode if you like...*/);
    }
    else {
        response.on("data", function (chunk) {
            str += chunk;
        });
        response.on("end", function () {
            console.log("[evfService] Got user info: " + str);
            deferred.resolve(str);
        });
    }
});

req.on("error", function (e) {
    deferred.reject(/*...with appropriate information, but status code is irrelevant [there isn"t one]...*/);
});

¹ The empty data event handler in the branch handling non-OK status codes is there because of this note in the documentation:

...if a 'response' event handler is added, then the data from the response object must be consumed, either by calling response.read() whenever there is a 'readable' event, or by adding a 'data' handler, or by calling the .resume() method. Until the data is consumed, the 'end' event will not fire. Also, until the data is read it will consume memory that can eventually lead to a 'process out of memory' error.

Since we're passing a function to https.get, we're hooking the 'response' event, which suggests we need to do one of those things (in this case, I've added a do-nothing data handler). Thanks to Nicolas2bert for pointing that out!.

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