Static file cache issues

[grimasod]

Current behavior

Multiple related issues

1. The static file default cache (maxAge) is 43 minutes
2. service-worker.js uses this default maxAge setting, it should be zero
3. Content-Type is not correctly set for service-worker.js

File: /core/scripts/server.js

const serve = (path, cache, options) => express.static(resolve(path), Object.assign({
  maxAge: cache && isProd ? 60 * 60 * 24 * 30 : 0
}, options))

(1) As stated in the Express docs, maxAge is in milliseconds (it's converted to seconds for the Response Header cache-control: max-age value)
https://expressjs.com/en/api.html#express.static

So this value 60 * 60 * 24 * 30 = 2592000 milliseconds converts to 2592 seconds = 43 minutes and 12 seconds. Presumably it was intended to be 30 days.

app.use('/service-worker.js', serve('dist/service-worker.js', {
  setHeaders: {'Content-Type': 'text/javascript; charset=UTF-8'}
}))

(2) The above function call only has 2 parameters, the middle one is missing. It should be a boolean, that determines whether or not to set the max-age value. Instead the second parameter is an object, which converts to True, so service-worker.js gets a max-age value when it shouldn't.

(Modern browsers might ignore this, but it's still better to have a zero value. It can also be overwritten by the web server, such as Nginx, but it should be correct by default)

(3) The third parameter, "options" is also missing , so the Content-Type doesn't get set. Furthermore, setHeaders must be a function, not an object. As described in the docs:
https://expressjs.com/en/api.html#setHeaders

Expected behavior

1. The static file default cache (maxAge) is 1 month (or other value?)
2. service-worker.js has zero max-age
3. Content-Type is set to "text/javascript" for service-worker.js

Steps to reproduce the issue

1. Open a browser tab/window with Developer Tools open on the Network tab
2. Browse to https://demo.storefrontcloud.io/service-worker.js
3. Select the service-worker.js file and note the following item in the Response Headers:
   "cache-control: public, max-age=2592"

Repository

Can you handle fixing this bug by yourself?

• YES
• NO

Preparing Pull Request

Which Release Cycle state this refers to? Info for developer.

Pick one option.

• This is a bug report for test version on https://test.storefrontcloud.io - In this case Developer should create branch from develop branch and create Pull Request 2. Feature / Improvement back to develop.
• This is a bug report for current Release Candidate version on https://next.storefrontcloud.io - In this case Developer should create branch from release branch and create Pull Request 3. Stabilisation fix back to release.
• This is a bug report for current Stable version on https://demo.storefrontcloud.io and should be placed in next stable version hotfix - In this case Developer should create branch from hotfix or master branch and create Pull Request 4. Hotfix back to hotfix.

Environment details

• Browser: Chrome 73
• OS: Mac
• Node: 8.11.4
• Code Version: all, including 1.8.4, Master, Develop

Additional information