node.js - In node.js how to check whether the particular write stream is opened or not

Question

Before opening the stream need to check whether the stream is already opened or not

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


});

Answer 1

流将open在打开时发出，因为这是异步的，无法判断它何时发出，您甚至可以编写类似的东西

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"});

open当他们准备好时，所有人都会发出事件。

如果您console.log在发出 open 时使用其中一个对象进行转储，您将看到一个具有许多属性的对象，例如_writableState保留写入状态的位置。

一种不太棒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.