What is readIntBE() Buffer Module in Node.js?
Buffer objects are used to represent a sequence of bytes of pre-determined size. They are similar to arrays but cannot be resized. Since the Buffer class is designed to handle raw binary data, it provides various methods, particularly for binary data.
The readIntBE method is used to read a specific number of bytes at an offset provided in the function’s arguments. The bytes read from the buffer are represented as a big-endian, two’s complement signed integer value supporting up to 48 bits of accuracy.
Syntax and parameters
The method can be accessed using the . notation on a buffer object. In the following example, buf is a Buffer object:
buf.readIntBE(offset, byteLength)
offsetis the number of bytes to skip before reading the buffer. It is initialized with 0 by default. Theoffsetmust be between0and(buf.length - byteLength).
buf.lengthis the size of the buffer, i.e. the number of elements in the buffer.
byteLengthis the number of bytes to be read. This number should be between0and6.
Return value
The function returns a big-endian, two’s complement signed integer value.
Example
We will demonstrate how to use the readIntBE in the following example:
const buf = Buffer.from([0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70, 0x80]);console.log(buf.readIntBE(0, 6).toString(16));console.log(buf.readIntBE(1, 6).toString(16));//console.log(buf.readIntBE(3, 6).toString(16));
- We first initialize the buffer using an array of hexadecimal numbers and the
.frommethod of theBufferobject. - In line 3, the offset is set as 0, and the bytes to be read are set as 6. The first 6 values are printed.
- In line 4, we provide an offset of 1. The first value is skipped, and the next 6 values are printed.
- You can comment out line 5 to check that the compiler throws an
ERR_OUT_OF_RANGE(out of range) error when the offset is greater than the limit we described above in the heading Syntax and Parameters.
The
toStringmethod is used to convert the result into text. We provide 16 as theradixargument of the function to convert the result into a hexadecimal representation.
