Node.js zlib.deflate() Method

The zlib.deflate() method is an inbuilt application programming interface of the Zlib module which is used to compress a chunk of data.

Syntax:

zlib.deflate( buffer, options, callback )

Parameters: This method accept three parameters as mentioned above and described below:

• buffer: It can be of type Buffer, TypedArray, DataView, ArrayBuffer, and string.
• options: It is an optional parameter that holds the zlib options.
• callback: It holds the callback function.

Return Value: It returns the chunk of data after compression.

Below examples illustrate the use of zlib.deflate() method in Node.js:

Example 1:

// Node.js program to demonstrate the
// deflate() method

// Including zlib module
const zlib = require("zlib");

// Declaring input and assigning
// it a value string
var input = "Geeks";

// Calling deflate method
zlib.deflate(input, (err, buffer) => {

  if (!err) {

    console.log(buffer.toString('base64'));
  }
  else {
    console.log(err);
  }
});
console.log("Data Compressed...");

Output:

Data Compressed...
eJxzT03NLgYABXQB8A==

Example 2:

// Node.js program to demonstrate the
// deflate() method

// Including zlib module
const zlib = require("zlib");

// Declaring input and assigning
// it a value string
var input = "Geeks";

// Calling deflate method
zlib.deflate(input, (err, buffer) => {

  if (!err) {

    console.log(buffer.toString('bas64'));
  }
  else {
    console.log(err);
  }
});
console.log("Data Compressed...");

Output:

Data Compressed...
buffer.js:631
  throw new ERR_UNKNOWN_ENCODING(encoding);
  ^

TypeError [ERR_UNKNOWN_ENCODING]: Unknown encoding: bas64
    at stringSlice (buffer.js:631:9)    
    at Buffer.toString (buffer.js:667:10)    
    at Deflate.zlib.deflate [as cb] 
(/home/runner/BeautifulMiserlySourcecode/index.js:17:24)
    at Deflate.zlibBufferOnEnd (zlib.js:133:10)
    at Deflate.emit (events.js:203:15)
    at Deflate.EventEmitter.emit (domain.js:448:20)
    at endReadableNT (_stream_readable.js:1143:12)
    at process._tickCallback (internal/process/next_tick.js:63:19)

Here, an error occurs in encoding the data so, error is thrown.

Reference: https://nodejs.org/api/zlib.html#zlib_zlib_deflate_buffer_options_callback