node.js - 在node.js中如何检查特定的写入流是否打开

Question

打开流之前需要检查流是否已经打开

var fs=require('fs');
var stream=fs.createWriteStream(filePath, {flags: 'a'});
stream.on('open',function(){


});

Answer 1

流在打开时会发出 open 因为这是异步的，所以无法知道它何时发出，您甚至可以编写类似的内容

var _path = "text.txt";
var stream1 = fs.createWriteStream(_path,{flags:"a"});
var stream2 = fs.createWriteStream(_path,{flags:"a"});
var stream3 = fs.createWriteStream(_path,{flags:"a"});
var streamN = fs.createWriteStream(_path,{flags:"a"});

当它们准备好时，所有的都会发出open事件。

如果在发出 open 时使用 console.log 转储其中一个对象，您将看到一个具有许多属性的对象，例如保留写入状态的 _writableState 。

一个不太好的方法是尝试下面的方法

var _path = "text.txt";
var stream = fs.createWriteStream(_path,{flags:"a"});
var stream2 = fs.createWriteStream(_path,{flags:"a"});

var lock = false; // try switching this , when opened and on other events to get the flow.