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Node.js Stream writable.setDefaultEncoding() Method

Last Updated : 12 Oct, 2021
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The writable.setDefaultEncoding() method is an inbuilt application programming interface of Stream module which is used to set the default encoding for a Writable stream. Syntax:
writable.setDefaultEncoding( encoding ) 
Parameters: This method accepts single parameter encoding which holds the encoding to be used for the Writable stream. Return Value: It returns the encoding which is made by default. Below examples illustrate the use of writable.setDefaultEncoding() method in Node.js: Example 1: javascript
// Node.js program to demonstrate the     
// writable.setDefaultEncoding() method  
const stream = require('stream');

// Creating a stream and creating 
// a write function
const writable = new stream.Writable({

  // Write function with its 
  // parameters
  write: function(chunk, encoding, next) {

    // Converting the chunk of
    // data to string
    console.log(chunk.toString());
    next();
  }
});

// Writing data
writable.write('hi');

// Calling setDefaultEncoding method
writable.setDefaultEncoding("utf8");
Output:
hi
Writable {
  _writableState:
   WritableState {
     objectMode: false,
     highWaterMark: 16384,
     finalCalled: false,
     needDrain: false,
     ending: false,
     ended: false,
     finished: false,
     destroyed: false,
     decodeStrings: true,
     defaultEncoding: 'utf8',
     length: 0,
     writing: false,
     corked: 0,
     sync: false,
     bufferProcessing: false,
     onwrite: [Function: bound onwrite],
     writecb: null,
     writelen: 0,
     bufferedRequest: null,
     lastBufferedRequest: null,
     pendingcb: 1,
     prefinished: false,
     errorEmitted: false,
     emitClose: true,
     autoDestroy: false,
     bufferedRequestCount: 0,
     corkedRequestsFree:
      { next: null,
        entry: null,
        finish: [Function: bound onCorkedFinish] } },
  writable: true,
  _write: [Function: write],
  domain: null,
  _events: [Object: null prototype] {},
  _eventsCount: 0,
  _maxListeners: undefined }
Here, the default value is returned in the output. Example 2: javascript
// Node.js program to demonstrate the     
// writable.setDefaultEncoding() method  
const stream = require('stream');

// Creating a stream and creating 
// a write function
const writable = new stream.Writable({

  // Write function with its 
  // parameters
  write: function(chunk, encoding, next) {

    // Converting the chunk of
    // data to string
    console.log(chunk.toString());
    next();
  }
});

// Writing data
writable.write('hi');

// Calling setDefaultEncoding method
writable.setDefaultEncoding("ascii");
Output:
hi
Writable {
  _writableState:
   WritableState {
     objectMode: false,
     highWaterMark: 16384,
     finalCalled: false,
     needDrain: false,     ending: false,
     ended: false,
     finished: false,
     destroyed: false,
     decodeStrings: true,
     defaultEncoding: 'ascii',
     length: 0,
     writing: false,
     corked: 0,
     sync: false,
     bufferProcessing: false,
     onwrite: [Function: bound onwrite],
     writecb: null,
     writelen: 0,
     bufferedRequest: null,
     lastBufferedRequest: null,
     pendingcb: 1,
     prefinished: false,
     errorEmitted: false,
     emitClose: true,
     autoDestroy: false,
     bufferedRequestCount: 0,
     corkedRequestsFree:
      { next: null,
        entry: null,
        finish: [Function: bound onCorkedFinish] } },
  writable: true,
  _write: [Function: write],
  domain: null,
  _events: [Object: null prototype] {},
  _eventsCount: 0,
  _maxListeners: undefined }
Here, the default value is "ascii". Reference: https://nodejs.org/api/stream.html#stream_writable_setdefaultencoding_encoding

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