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Support configured charsets for static content #106

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6566f89
Support configured file charsets
vibhor-aggr Jun 10, 2026
daf48bd
Address charset review feedback
vibhor-aggr Jun 10, 2026
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7 changes: 4 additions & 3 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -48,10 +48,11 @@ app.use(staticCache(path.join(__dirname, 'public'), {
- `options.maxAge` (int) - cache control max age for the files, `0` by default.
- `options.cacheControl` (str) - optional cache control header. Overrides `options.maxAge`.
- `options.buffer` (bool) - store the files in memory instead of streaming from the filesystem on each request.
- `options.gzip` (bool) - when request's accept-encoding include gzip, files will compressed by gzip.
- `options.usePrecompiledGzip` (bool) - try use gzip files, loaded from disk, like nginx gzip_static
- `options.gzip` (bool) - when the request's Accept-Encoding includes gzip, files will be compressed using gzip.
- `options.charset` (str | function) - optional charset appended to `Content-Type`. If a function is supplied, it receives `(file, type)`, where `file` is the relative file path, and can return a charset per file.
- `options.usePrecompiledGzip` (bool) - try to use gzip files, loaded from disk, like nginx gzip_static
- `options.alias` (obj) - object map of aliases. See below.
- `options.prefix` (str) - the url prefix you wish to add, default to `''`.
- `options.prefix` (str) - the URL prefix you wish to add, defaults to `''`.
- `options.dynamic` (bool) - dynamic load file which not cached on initialization.
- `options.filter` (function | array) - filter files at init dir, for example - skip non build (source) files. If array set - allow only listed files
- `options.preload` (bool) - caches the assets on initialization or not, default to `true`. always work together with `options.dynamic`.
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9 changes: 8 additions & 1 deletion index.js
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Expand Up @@ -186,7 +186,14 @@ function loadFile(name, dir, options, files) {

obj.cacheControl = options.cacheControl
obj.maxAge = (typeof obj.maxAge === 'number' ? obj.maxAge : options.maxAge) || 0
obj.type = obj.mime = mime.lookup(pathname) || 'application/octet-stream'
var type = mime.lookup(pathname) || 'application/octet-stream'
var charset = typeof options.charset === 'function'
? options.charset(name, type)
: options.charset
obj.mime = type
obj.type = charset
? type + '; charset=' + charset
: type
obj.mtime = stats.mtime
obj.length = stats.size
obj.md5 = crypto.createHash('md5').update(buffer).digest('base64')
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70 changes: 70 additions & 0 deletions test/index.js
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Expand Up @@ -150,6 +150,76 @@ describe('Static Cache', function () {
})
})

it('should serve files with configured charset', function (done) {
var app = new Koa()
app.use(staticCache(path.join(__dirname, '..'), {
charset: 'iso-8859-1',
filter(file) {
return file === 'README.md'
}
}))
var server = app.listen()

Comment on lines +153 to +162

@sourcery-ai sourcery-ai Bot Jun 10, 2026

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suggestion (testing): Add a test to cover unknown MIME types with a configured charset to ensure the fallback MIME lookup behavior stays intact.

Specifically, please add a test where the served file has an unknown extension (e.g. foo.bin) and options.charset is set, and assert that the Content-Type is 'application/octet-stream; charset=iso-8859-1' (or equivalent). This will protect the fallback MIME type and charset concatenation behavior from regressions.

Suggested implementation:

    .expect('Content-Type', 'text/markdown; charset=iso-8859-1')
    .expect(200, done)
  })

  it('should serve files with configured charset for unknown mime types', function (done) {
    var app = new Koa()
    app.use(staticCache(path.join(__dirname, '..'), {
      charset: 'iso-8859-1',
      filter(file) {
        return file === 'foo.bin'
      }
    }))
    var server = app.listen()

    request(server)
    .get('/foo.bin')
    .expect('Content-Type', 'application/octet-stream; charset=iso-8859-1')
    .expect(200, done)
  })

For this test to pass, ensure there is a foo.bin file in the directory being served (based on your existing tests, likely the project root: path.join(__dirname, '..')). The file can be empty or contain arbitrary data; it only needs to exist so that the middleware can serve it and trigger the fallback MIME type logic.

request(server)
.get('/README.md')
.expect('Content-Type', 'text/markdown; charset=iso-8859-1')
.expect(200, done)
})

it('should serve files with configured charset for unknown mime types', function (done) {
var app = new Koa()
app.use(staticCache(path.join(__dirname, '..'), {
charset: 'iso-8859-1',
filter(file) {
return file === 'Makefile'
}
}))
var server = app.listen()

request(server)
.get('/Makefile')
.expect('Content-Type', 'application/octet-stream; charset=iso-8859-1')
.expect(200, done)
})

it('should serve files with function configured charset', function (done) {
var app = new Koa()
app.use(staticCache(path.join(__dirname, '..'), {
charset(file, type) {
return file === 'README.md' && type === 'text/markdown'
? 'windows-1252'
: undefined
},
filter(file) {
return file === 'README.md'
}
}))
var server = app.listen()

request(server)
.get('/README.md')
.expect('Content-Type', 'text/markdown; charset=windows-1252')
.expect(200, done)
})
Comment on lines +199 to +203

@sourcery-ai sourcery-ai Bot Jun 10, 2026

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suggestion (testing): Add coverage for the case where the charset function returns undefined to verify that no charset is appended.

The current test only covers when the charset function returns a string. Please also add a case where charset(file, type) returns undefined (or another falsy value) and assert that the Content-Type header omits ; charset=.... This documents the fallback behavior and guards against regressions like accidentally sending ; charset=undefined.

Suggested change
request(server)
.get('/README.md')
.expect('Content-Type', 'text/markdown; charset=windows-1252')
.expect(200, done)
})
request(server)
.get('/README.md')
.expect('Content-Type', 'text/markdown; charset=windows-1252')
.expect(200, done)
})
it('should not append charset when charset function returns undefined', function (done) {
var app = new Koa()
app.use(staticCache(path.join(__dirname, '..'), {
charset(file, type) {
// explicit undefined to exercise the "no charset" path
return undefined
},
filter(file) {
return file === 'README.md'
}
}))
var server = app.listen()
request(server)
.get('/README.md')
.expect('Content-Type', 'text/markdown')
.expect(200, done)
})


it('should not append charset when charset function returns undefined', function (done) {
var app = new Koa()
app.use(staticCache(path.join(__dirname, '..'), {
charset() {
return undefined
},
filter(file) {
return file === 'Makefile'
}
}))
var server = app.listen()

request(server)
.get('/Makefile')
.expect('Content-Type', 'application/octet-stream')
.expect(200, done)
})

it('should serve recursive files', function (done) {
request(server)
.get('/test/index.js')
Expand Down