节点.js流可读.已破坏属性

原文:https://www . geesforgeks . org/node-js-stream-可读-已销毁-property/

可读.销毁属性是 Stream 模块的内置应用编程接口，用于检查可读.销毁()函数是否被调用。

语法:

readable.destroyed


返回值:如果可读则返回真，否则返回假。

下面的例子说明了在 Node.js 中可读.销毁属性的使用:

例 1:

// Node.js program to demonstrate the     
// readable.destroyed Property  
// Include fs module
const fs = require("fs");
// Constructing readable stream
const readable = fs.createReadStream("input.txt");
// Instructions for reading data
readable.on('readable', () => {
  let chunk;
  // Using while loop and calling
  // read method with parameter
  while (null !== (chunk = readable.read())) {
    // Displaying the chunk
    console.log(`read: ${chunk}`);
  }
});
// Handling error event
readable.on('error', err => {
    console.log(err);
});
// Calling destroy method
// with parameter
readable.destroy('error');
// Displays that the stream is 
// destroyed
console.log("Stream destroyed");
// Calling readable.destroyed
// Property
readable.destroyed;


输出:

Stream destroyed
true
error


例 2:

// Node.js program to demonstrate the     
// readable.destroyed Property  
// Include fs module
const fs = require("fs");
// Constructing readable stream
const readable = fs.createReadStream("input.txt");
// Instructions for reading data
readable.on('readable', () => {
  let chunk;
  // Using while loop and calling
  // read method with parameter
  while (null !== (chunk = readable.read())) {
    // Displaying the chunk
    console.log(`read: ${chunk}`);
  }
});
// Displays that the stream is 
// destroyed
console.log("Program completed!!");
// Calling readable.destroyed
// Property
readable.destroyed;


输出:

Program completed!!
false
read: hello


所以，这里 readable.destroy()方法在 readable.destroyed 属性之前不被调用，所以它返回 false。

参考:https://nodejs . org/API/stream . html # stream _ readable _ 销毁