Compressing a JSON string? (And strings in general)

Question

How should I go about compressing a very large JSON string to transmit over websockets? (Also later to store in localStorage)

It's already minified, but I need something that can do this: http://www.unit-conversion.info/texttools/compress/ (I tried poking about in the source there and couldn't figure it out)

Answer 1

You can compress any kind of binary data (strings, Buffers) with Node.js, no external deps required, using the zlib module.

You can use either gzip or deflate compression algorithms, depending on your needs.

Example

(shamelessly stolen from Node.js' website)

const zlib = require('zlib')
const input = JSON.stringify({ some: 'json-data' })

zlib.deflate(input, (err, buffer) => {
  if (err) {
    console.log('u-oh')
  }

  // Send buffer as string to client using my imaginary io object
  io.send(buffer.toString('base64'))
})

Update: It might be better to just enable HTTP compression on the transport layer instead of compressing and decompressing the data on your own.