Koa Compress
Compress middleware for Koa
Example
const compress = require('koa-compress')
const Koa = require('koa')
const app = new Koa()
app.use(compress({
filter (content_type) {
return /text/i.test(content_type)
},
threshold: 2048,
gzip: {
flush: require('zlib').constants.Z_SYNC_FLUSH
},
deflate: {
flush: require('zlib').constants.Z_SYNC_FLUSH,
},
br: false // disable brotli
}))
Options
filter<Function>
function (mimeType: string): Boolean {
}
An optional function that checks the response content type to decide whether to compress. By default, it uses compressible.
options.threshold<String|Number|Function>
Minimum response size in bytes to compress or a function that returns such response (see below).
Default 1024
bytes or 1kb
.
options[encoding]<Object|Function>
The current encodings are, in order of preference: br
, gzip
, deflate
.
Setting options[encoding] = {}
will pass those options to the encoding function.
Setting options[encoding] = false
will disable that encoding.
It can be a function that returns options (see below).
options.br
Brotli compression is supported in node v11.7.0+, which includes it natively.
options.defaultEncoding<String>
An optional string, which specifies what encoders to use for requests without
Accept-Encoding.
Default idenity
.
The standard dictates to treat such requests as *
meaning that all compressions are permissible,
yet it causes very practical problems when debugging servers with manual tools like curl
, wget
, and so on.
If you want to enable the standard behavior, just set defaultEncoding
to *
.
Manually turning compression on and off
You can always enable compression by setting ctx.compress = true
.
You can always disable compression by setting ctx.compress = false
.
This bypasses the filter check.
app.use((ctx, next) => {
ctx.compress = true
ctx.body = fs.createReadStream(file)
})
ctx.compress
can be an object similar to options
above, whose properties (threshold
and encoding options)
override the global options
for this response and bypass the filter check.
Functional properties
Certain properties (threshold
and encoding options) can be specified as functions. Such functions will be called
for every response with three arguments:
type
— the same asctx.response.type
(provided for convenience)size
— the same asctx.response.length
(provided for convenience)ctx
— the whole context object, if you want to do something unique
It should return a valid value for that property. It is possible to return a function of the same shape, which will be used to calculate the actual property.
Example:
app.use((ctx, next) => {
// ...
ctx.compress = (type, size, ctx) => ({
br: size && size >= 65536,
gzip: size && size < 65536
})
ctx.body = payload
})
Read all about ctx
in https://koajs.com/#context and ctx.response
in https://koajs.com/#response