Node.js 可读流可读事件
原文:https://www . geesforgeks . org/node-js-ready-stream-ready-event/
可读流中的“可读”事件在数据可用时发出，以便可以从流中读取数据，或者可以通过添加“可读”事件的侦听器来发出，该侦听器将导致数据被读取到内部缓冲区中。
语法:
Event: 'readable'
下面的例子说明了可读事件在 Node.js 中的使用:
例 1:
// Node.js program to demonstrate the
// readable event
// Including fs module
const fs = require('fs');
// Constructing readable stream
const readable = fs.createReadStream("input.txt");
// Handling readable event
readable.on('readable', () => {
let chunk;
// Using while loop and calling
// read method
while (null !== (chunk = readable.read())) {
// Displaying the chunk
console.log(`read: ${chunk}`);
}
});
console.log("Done...");
输出:
Done...
read: GeeksforGeeks
例 2:
// Node.js program to demonstrate the
// readable event
// Including fs module
const fs = require('fs');
// Constructing readable stream
const readable = fs.createReadStream("input.txt");
// Handling readable event
readable.on('readable', () => {
console.log(`readable: ${readable.read()}`);
});
// Handling end event
readable.on('end', () => {
console.log('Stream ended');
});
console.log("Done.");
输出:
Done.
readable: GeeksforGeeks
readable: null
Stream ended
这里，发出 end 事件，因此返回 null。
参考:T2】https://nodejs.org/api/stream.html#stream_event_readable
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