brotli: set default quality to 4 closes #121

README.md

@@ -59,6 +59,7 @@ Setting `options[encoding] = false` will disable that encoding.
 #### options<span></span>.br
 
 [Brotli compression](https://en.wikipedia.org/wiki/Brotli) is supported in node v11.7.0+, which includes it natively.
+As of v5.1.0, the default quality level is 4 for performance reasons.
 
 ### options.defaultEncoding\<String\>
 

__tests__/defaults.js

@@ -0,0 +1,12 @@
+
+const assert = require('assert')
+const zlib = require('zlib')
+
+const createCompressMiddleware = require('..')
+
+test('default brotli param quality should be 4', () => {
+  const middleware = createCompressMiddleware()
+  assert(Array.isArray(middleware.preferredEncodings))
+  assert(middleware.encodingOptions)
+  assert.strictEqual(middleware.encodingOptions.br[zlib.constants.BROTLI_PARAM_QUALITY], 4)
+})

lib/encodings.js

@@ -21,6 +21,14 @@ Encodings.encodingMethods = {
   br: zlib.createBrotliCompress
 }
 
+Encodings.encodingMethodDefaultOptions = {
+  gzip: {},
+  deflate: {},
+  br: {
+    [zlib.constants.BROTLI_PARAM_QUALITY]: 4
+  }
+}
+
 // how we treat `Accept-Encoding: *`
 Encodings.wildcardAcceptEncoding = ['gzip', 'deflate']
 // our preferred encodings

lib/index.js

@@ -31,8 +31,22 @@ module.exports = (options = {}) => {
 
   // `options.br = false` would remove it as a preferred encoding
   const preferredEncodings = Encodings.preferredEncodings.filter((encoding) => options[encoding] !== false && options[encoding] !== null)
+  const encodingOptions = {}
+  preferredEncodings.forEach((encoding) => {
+    encodingOptions[encoding] = {
+      ...Encodings.encodingMethodDefaultOptions[encoding],
+      ...(options[encoding] || {})
+    }
+  })
+
+  Object.assign(compressMiddleware, {
+    preferredEncodings,
+    encodingOptions
+  })
+
+  return compressMiddleware
 
-  return async (ctx, next) => {
+  async function compressMiddleware (ctx, next) {
     ctx.vary('Accept-Encoding')
 
     await next()
@@ -76,7 +90,7 @@ module.exports = (options = {}) => {
     ctx.res.removeHeader('Content-Length')
 
     const compress = Encodings.encodingMethods[encoding]
-    const stream = ctx.body = compress(options[encoding])
+    const stream = ctx.body = compress(encodingOptions[encoding])
 
     if (body instanceof Stream) {
       body.pipe(stream)