Node.js Buffer.readInt16LE() 方法

Buffer.readUInt16LE() 方法是 Buffer 模块内的 Buffer 类的内置应用程序编程接口，用于从分配的缓冲区中以 Little Endian 格式在指定偏移处读取 16 位值。

句法：

Buffer.readUInt16LE(offset)

参数：此方法接受单个参数偏移量，它指定在读取之前要跳过的字节数，或者只是表示缓冲区中的索引。 offset 的值是0 <= offset <= Buffer.length – 2 。它的默认值为 0。

返回值：此方法以小端格式返回从缓冲区读取的整数值。

以下示例说明了 Node.js 中 Buffer.readUInt16LE() 方法的使用：

示例 1：

// Node program to demonstrate the  
// Buffer.readInt16LE() Method
   
// Allocating buffer from array
const buf = Buffer.from([0x21, 0x09, 0x19, 0x98]);
  
// Printing allocated buffer
console.log(buf);
   
// Reading 16bits data from the buffer
// and printing it as a string
console.log(buf.readUInt16LE(0).toString(16));
console.log(buf.readUInt16LE(1).toString(16));
console.log(buf.readUInt16LE(2).toString(16));

输出：

921
1909
9819

示例 2：

// Node program to demonstrate the  
// Buffer.readInt16LE() Method
   
// Allocating buffer from array
const buf = Buffer.from([0x21, 0x09, 0x19, 0x98]);
  
// Printing allocated buffer
console.log(buf);
   
// Reading 16bits data from the buffer
// and printing it as a string
console.log(buf.readUInt16LE(0).toString(16));
console.log(buf.readUInt16BE(0).toString(16));
console.log(buf.readUInt16LE(1).toString(16));
console.log(buf.readUInt16BE(1).toString(16));
console.log(buf.readUInt16LE(2).toString(16));
console.log(buf.readUInt16BE(2).toString(16));

输出：

921
2109
1909
919
9819
1998

示例 3：

// Node program to demonstrate the  
// Buffer.readInt16LE() Method
   
// Allocating buffer from array
const buf = Buffer.from([0x21, 0x09, 0x19, 0x98]);
  
// Printing allocated buffer
console.log(buf);
   
// Reading 16bits data from the buffer
// and printing it as a string
console.log(buf.readUInt16LE(0).toString(16));
console.log(buf.readUInt16LE(1).toString(16));
console.log(buf.readUInt16LE(2).toString(16));
   
// Wrong index is provoded to produce error
console.log(buf.readUInt16LE(3).toString(16));

输出：

921
1909
9819
internal/buffer.js:49
  throw new ERR_OUT_OF_RANGE(type || 'offset',
  ^
RangeError [ERR_OUT_OF_RANGE]: The value of "offset" is out of range.
It must be >= 0 and <= 2. Received 3
    at boundsError (internal/buffer.js:49:9)
    at Buffer.readUInt16LE (internal/buffer.js:128:5)
    . . .

注意：以上程序将使用node index.js命令编译运行。

参考： https://nodejs.org/api/buffer.html#buffer_buf_readuint16le_offset