Node.jsStream可写.write()方法

原文:https://www . geesforgeks . org/node-js-stream-write-write-method/

write . write()方法是 Stream 模块的内置应用编程接口，用于将一些数据写入可写流。一旦数据被完全处理，就调用回调函数。

语法:

writable.write( chunk, encoding, callback)


参数:该方法接受三个参数，如上所述，如下所述:

• Chunk: is an optional data writing. The value of the block must be a string, buffer or Uint 8 array. For object mode, the block value can be any value other than null.


• Code: If the chunk is a string value, the code value is saved.


• Callback: is an optional callback function of the stream.

返回值:如果在此方法返回真之前发出‘排空’事件，则返回假。

以下示例说明了在 Node.js 中使用可写. write()方法:

例 1:

// Node.js program to demonstrate the     
// writable.write() method  
// Including stream module
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();
  }
});
// Calling write method with
// all its parameter
writable.write("GfG", "utf8", () => {
     console.log("CS-Portal!");
});


输出:

GfG
true
CS-Portal!


例 2:

// Node.js program to demonstrate the     
// writable.write() method  
// Including stream module
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();
  }
});
// Calling write method with one
// parameter
writable.write('GeeksforGeeks');


输出:

GeeksforGeeks
true


参考:https://nodejs . org/API/stream . html # stream _ write _ chunk _ encoding _ callback