Node.js 中的流 writable.writableLength 属性
该writable.writableLength属性用于显示队列中准备写入的字节数或对象数。这用于根据highWaterMark的状态检查数据。
语法
writeable.writableLength
示例1
创建一个具有名称的文件-writableLength.js并复制以下代码片段。创建文件后，使用以下命令运行此代码，如下例所示-
node writableLength.js
//演示writable.writableLength方法的程序
const stream = require('stream');
//创建具有可写性的数据流
const writable = new stream.Writable({
//从流中写入数据
write: function(chunk, encoding, next) {
//转换要显示的数据块
console.log(chunk.toString());
next();
}
});
//写入数据-不在缓冲队列中
writable.write('Hi - This data will not be counted');
//调用cork()函数
writable.cork();
//再次写入一些数据
writable.write('Welcome to nhooo !');
writable.write('SIMPLY LEARNING ');
writable.write('This data will be corked in the memory');
//打印队列数据的长度
console.log(writable.writableLength);输出结果C:\home\node>> node writableLength.js Hi - This data will not be counted 81
在控制台中计算并打印被塞住并在缓冲区队列内的数据。
示例
让我们再看一个例子。
//演示writable.cork()方法的程序
const stream = require('stream');
//创建具有可写性的数据流
const writable = new stream.Writable({
//从流中写入数据
write: function(chunk, encoding, next) {
//转换要显示的数据块
console.log(chunk.toString());
next();
}
});
//写入数据-不在缓冲队列中
writable.write('Hi - This data will not be counted');
//调用cork()函数
writable.cork();
//再次写入一些数据
writable.write('Welcome to nhooo !');
writable.write('SIMPLY LEARNING ');
writable.write('This data will be corked in the memory');
//打印队列数据的长度
console.log(writable.writableLength);
//从缓冲内存中刷新数据
writable.uncork()
console.log(writable.writableLength);输出结果C:\home\node>> node writableLength.js Hi - This data will not be counted 81 Welcome to nhooo ! SIMPLY LEARNING This data will be corked in the memory 0
由于现在数据已经在uncork().队列不会保存任何数据，这就是返回长度为0的原因。