Node.js - Buffer.readUIntBE() Method

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The NodeJS Buffer.readUIntBE() method will read a number of bytes as per the byte length and offset and return the unsigned integer in big endian format from a buffer used.

Syntax

Following is the syntax of the Node.JS Buffer.readUIntBE() Method −

buf.readUIntBE(offset, byteLength)

Parameters

This method accepts two parameters. The same is explained below.

• offset − The offset that indicates the position to start reading. The offset is greater than or equal to 0 and also less than or equal to buffer.length-bytelength. The default value is 0.

• byteLength − The number of bytes you want to read. The byteLength has to be between 0 to 6.

Return value

This method returns the unsigned integer in big endian format with a bytelength number of bytes at a given offset value from the buffer.

Example

To create a buffer, we are going to make use of NodeJS Buffer.from() method −

const buffer = Buffer.from([11, 12, 13, 14, 15, 16]);
console.log(buffer);
console.log(buffer.readUIntBE(0, 2));

Output

The offset we have used with this method is 0. The bytelength used is 2. So from 0th offset it will read the bytes with bytelength 2 and return the result in big endian format.

<Buffer 0b 0c 0d 0e 0f 10>
2828

Example

In this example let us print the output we get in hexadecimal form as shown below −

const buffer = Buffer.from([11, 12, 13, 14, 15, 16]);
console.log(buffer);
console.log(buffer.readUIntBE(0, 2).toString(16));

Output

<Buffer 0b 0c 0d 0e 0f 10>
b0c

Example

As we know we can make use of offset from 0 to buffer.length-bytelength. So if the buffer length is 6, and bytelength used is 6 we can use offset as 0. Using value greater than 0 will give you error: ERR_OUT_OF_RANGE.

const buffer = Buffer.from([11, 12, 13, 14, 15, 16]);
console.log(buffer);
console.log("The buffer length is :"+ buffer.length);
console.log(buffer.readUIntBE(1, 6).toString(16));

Output

<Buffer 0b 0c 0d 0e 0f 10>
The buffer length is :6
internal/buffer.js:58
   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 <= 0. Received 1
   at boundsError (internal/buffer.js:58:9)
   at readUInt48BE (internal/buffer.js:177:5)
   at Buffer.readUIntBE (internal/buffer.js:157:12)
   at Object.<anonymous> (C:\nodejsProject\src\testbuffer.js:5:20)
   at Module._compile (internal/modules/cjs/loader.js:816:30)
   at Object.Module._extensions..js (internal/modules/cjs/loader.js:827:10)
   at Module.load (internal/modules/cjs/loader.js:685:32)
   at Function.Module._load (internal/modules/cjs/loader.js:620:12)
   at Function.Module.runMain (internal/modules/cjs/loader.js:877:12)
   at internal/main/run_main_module.js:21:11