Node.js zlib.bytesWritten 属性

zlib.bytesWritten 属性是 zlib 模块的应用程序编程接口，用于指定在处理字节之前写入引擎的字节数（压缩或解压缩，适用于派生类）。

句法：

zlib.bytesWritten

返回值：它返回写入引擎的字节数。

下面的例子说明了在 Node.js 中zlib.bytesWritten 方法的使用：

示例 1：

// Node.js program to demonstrate the     
// zlib.bytesWritten Property
  
// Including assert and zlib 
// module
var zlib = require('zlib');
var assert = require('assert');
  
// Input to be written
const input = Buffer.from('0123456789012345678901');
  
// Calling deflate method
zlib.deflate(input, (err, deflatedBuffer) => {
  assert(!err);
  
  // Declaring buffer and numberRead
  var numberRead = 0;
  var buffers = [];
  
  // Creating a zip object
  var stream = zlib.createGzip()
  
    // Data event
    .on('data', function(chunk) {
     buffers.push(chunk);
     numberRead += chunk.length;
    })
  
    // end event
    .on('end', function() {
       
      // Calling bytesWritten property
      console.log(stream.bytesWritten);
       
      })
    .end(deflatedBuffer);
});

输出：

21

示例 2：

// Node.js program to demonstrate the     
// zlib.bytesWritten property
   
// Including zlib module
var zlib = require('zlib');
   
// Input to be written
const input = Buffer.from('NidhiSingh1352');
   
// Calling deflateRaw method
zlib.deflateRaw(input, (err, buffer) => {
   
  // Creating a Deflate object
  var zlibs = zlib.Deflate()
   
    // Data event
    .on('data', function(chunk) {})
   
    // end event
    .on('end', function() {
   
      // Calling bytesWritten property
      console.log(zlibs.bytesWritten);
   
    })
   .end(buffer);
});

输出：

16

参考： https://nodejs.org/api/zlib.html#zlib_zlib_byteswritten