What is the writeUInt16BE function in Node.js?
The writeUInt16BE function in Node.js comes with the Buffer module and is used to write a 16-bit unsigned integer in the Big Endian format to a buffer at a specified offset.
In the Big Endian format, the least significant bits are written last. In Little Endian format, this order is reversed. For example, the 32-bit hex number AB CD AD BD would be represented as BD AD CD AB in Little Endian format, and as AB CD AD BD in Big Endian format.
Syntax
To use the writeUInt16BE function, we need a pre-allocated buffer. For this tutorial, we have named it mybuffer. The following syntax is used to use the writeUInt16BE function:
mybuffer.writeUInt16BE(value, offset);
Parameters
The writeUInt16BE function takes in two parameters:
value: the unsigned 16-bit integer that needs to be written to a pre-allocated buffer.offset(optional): the offset at or the number of bytes after whichvaluewill be written to in the buffer. The minimum value ofoffsetis 0, and its maximum value is two less than the value ofmybuffer.len, which is the number of bytes in the buffer.
If
offsetis not specified, it is assumed to be 0 by default. If the value ofoffsetis out of the prescribed range, theERR_OUT_OF_RANGEerror is thrown. If thevalueis greater than 16 bits, the function exhibits undefined behavior.
Return value
The writeUInt16BE function returns the sum of the offset and the number of bytes written to the buffer upon successful execution.
Example
The program below allocates a buffer that is 6 bytes long. Subsequently, it uses the writeUInt16BE function to write a 16-bit unsigned integer to mybuffer at a specified offset, then prints the current state of mybuffer using the console.log function.
The program fills mybuffer with three 16-bit unsigned integers and prints its final state before terminating.
mybuffer = Buffer.alloc(6);console.log(mybuffer);mybuffer.writeUInt16BE(0xabcd, 0);console.log(mybuffer);mybuffer.writeUInt16BE(0xdbac, 2);console.log(mybuffer);mybuffer.writeUInt16BE(0xadeb, 4);console.log(mybuffer);
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