Node.js 流。可写关闭事件
原文:https://www . geesforgeks . org/node-js-stream-written-close-event/
溪流。可写关闭事件是 stream 模块的内置应用编程接口，用于在关闭 Stream 及其任何隐藏资源(例如，文件描述符)时发出。这个事件意味着不会发出更多的事件，并且不会进行进一步的计算。
语法:
Event: 'close'
返回值:如果在此事件后正在调用 writable.destroy()方法或正在关闭文件描述符，则发出此事件，否则不发出。
下面的例子说明了流的使用。Node.js 中的可写关闭事件:
例 1:
// Node.js program to demonstrate the
// close event
// 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();
}
});
// Writing data
writable.write('GeeksforGeeks');
// Emitting close event
writable.on('close', () => {
console.log("No further operations will be performed!");
});
// Calling destroy function
writable.destroy();
// Shows that the program ends
console.log("program is ended.");
输出:
GeeksforGeeks
program is ended.
No further operations will be performed!
在上面的示例中，在 close 事件之后调用了 writable.destroy()方法，因此它被发出。
例 2:
// Node.js program to demonstrate the
// close event
// 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();
}
});
// Writing data
writable.write('GeeksforGeeks');
// Emitting close event
writable.on('close', () => {
console.log("No further operations will be performed!");
});
// Shows that the program ends
console.log("program is ended.");
输出:
GeeksforGeeks
program is ended.
因此，这里不调用 writable.destroy()函数，因此不执行 close 事件。
参考:T2】https://nodejs.org/api/stream.html#stream_event_close
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