Next.js: Can't get the status code on client side

[lcswillems]

Bug report

Describe the bug

I use this code to get the status code:

Page.getInitialProps = ({ res, err }) => {
  const statusCode = res ? res.statusCode : err ? err.statusCode : null;
  return { statusCode };
};

but it doesn't always give me the status code.

To Reproduce

1. Clone this repository: https://github.com/lcswillems/next-bug

2. yarn dev

3. Go to http://localhost:3000/djhfdkfjkh (an error page):

The status code is 404.

1. Go to the home page by clicking on the link

2. Go back to the error page by clicking on the back history arrow:

1. The status code is now null.

Expected behavior

I would expect it to be 404.

System information

• OS: linux
• Browser (if applies) : chrome
• Version of Next.js: 9.0.7

[c0b41]

getInitialProps only call server side.

[lcswillems]

No, it is called on server side and client side. In my example, it is called on both.

[timneutkens]

res is only available on the server side so it's expected and not a bug based on your code. However it seems that you're referring to /_error and that the documentation is slightly different from the actual getInitialProps we use internally. The correct method would be:

Page.getInitialProps = ({ res, err }) => {
  const statusCode = res && res.statusCode ? res.statusCode : err ? err.statusCode : 404
  return { statusCode };
};

To split that out:

if(res && res.statusCode) {
  return res.statusCode
} else {
  if(err) {
    return err.statusCode
  }
  return 404
}

If /_error is rendered without an err it's a 404 basically. I'll update the docs!

[timneutkens]

Fixed in https://github.com/zeit/next.js/commit/0bcd1fc39bb07f67b94238a0e867e9c3fe73a163

Good catch! Thanks 🙏

[lcswillems]

Okay thank you for your fast answer!