Webpack-dev-server: PR #1696 Introduced a breaking change in v3.3.0 to previous proxy bypass implementations.

Created on 22 Aug 2019 · 5Comments · Source: webpack/webpack-dev-server

Operating System: Mac OSX High Sierra
Node Version: 10.16.0
NPM Version: 6.9.0
webpack Version: 4.36.1
webpack-dev-server Version: 3.7.2
Browser: Chrome 74.0.3729.169

[ ] This is a bug
[x] This is a modification request

Code

// webpack.config.js
...
config.devServer.proxy = {
    '**': {
        bypass(request) {
            if (request.headers.accept && request.headers.accept.includes('html')) {
                console.log('HTML', request.headers, request.url)
                return '/index.html';
            }
            console.log('API', request.headers, request.url)
            return false;
        },
        target: `http://localhost:${apiPort}`
    }
};
...

Expected Behavior

non-html requests are proxied to the target url.

Actual Behavior

The proxy middleware sets the request url as null if the bypass function returns a boolean, resulting in a 404 on page load.

For Bugs; How can we reproduce the behavior?

In PR #1696 , the actual behavior is listed as the previously intended behavior. This Issue is only to add a breaking change notice to the 3.3.0 release notes because previous consumers relied on an api which had its functionality changed in a non backwards compatible way.