Node.js Stream writable.setDefaultEncoding() Method

Last Updated : 12 Oct, 2021

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:

// 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:

// 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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