does-it-fit

Determine whether an HTTP endpoint's TCP response fits within minimum constraints

Example

const dif = require('does-it-fit')

dif('http://google.com', function (err, answer) {
  if (err) { 
    console.error('oh noes!', err)
    return
  }
  console.log(answer)
})

API

require('does-it-fit') => (url, opts, cb(err, result))

opts

constraints

Array of bytes - index of each matches labels Default: [536, 1024, 14336, 66560]

labels

Array of labels matching byte windows, Default: ['First TCP Segment', 'First Ethernet Packet', 'First TCP Roundtrip', 'First TCP Frame']

ssl

Add SSL overhead (default: true)

gzip

GZIP the body (default: true)

sslCost

Estimated amount of bytes for SSL overhead (default: 40)

gzipLevel

Compression level: 1-9. Defaults to Node's default gzip level

result

total

Total estimated bytes sent along TCP connection for endpoint

fits

Relevant TCP constraint (First TCP Segment, First Ethernet Packet, First TCP Roundtrip, First TCP Frame or No target TCP constraints)

headers

Size of headers

body

Size of body (after gzipping, if enabled)

emulatedSslSize

Estimated size of SSL overhead (as set by sslCost)

emulateGzip

Whether GZIP was emulated (disabled with noGzip)

gzipLevel

The compression level applied, only added if emulateGzip is true

CLI

npm install -g does-it-fit

does-it-fit http://google.com

-h              Help/Usage

-a              Show all values (instead of just total size and what it fits)

--constraints   Array of bytes (as quoted JSON) - index of each matches labels
                Default: [536, 1024, 14336, 66560]

--labels        Array of labels (as quoted JSON) matching byte windows, Default:
                [ 'First TCP Segment', 'First Ethernet Packet', 
                  'First TCP Roundtrip', 'First TCP Frame' ]

--no-ssl        Don't add SSL overhead

--no-gzip       Don't GZIP the body

--ssl-cost      Estimated amount of bytes for SSL overhead (default: 40)

--gzip-level    Compression level: 1-9. Defaults to Node's default gzip level

Test

npm test

Acknowledgements

• Yoshua Wuyts
• Sponsored by nearForm

License

MIT