Node.js | Buffer.readUInt32LE() Method

Last Updated : 30 Dec, 2019

The Buffer.readUInt32LE() method is an inbuilt application programming interface of class Buffer within the Buffer module which is used to read 32-bit value from an allocated buffer at a specified offset in little endian format. Syntax:

Buffer.readUInt32LE( offset )

Parameters: This method accept single parameter offset which specifies the number of bytes to skip before read or simply signify the index in the buffer. The value of offset lies 0 <= offset <= Buffer.length - 4. Its default value is 0. Return Value: This method returns an integer value that read from buffer in little endian format. Below examples illustrate the use of Buffer.readUInt32LE() method in Node.js: Example 1:

javascript

// Node program to demonstrate the   // Buffer.readUInt32LE() Method   // Allocating buffer from array const buf = Buffer.from([0x21, 0x09, 0x19,              0x98, 0x16, 0x09, 0x19, 0x96]);  // Printing allocated buffer console.log(buf);   // Reading 32bits data from the buffer // and printing it as a string console.log(buf.readUInt32LE(0).toString(16)); console.log(buf.readUInt32LE(1).toString(16)); console.log(buf.readUInt32LE(2).toString(16)); console.log(buf.readUInt32LE(3).toString(16)); console.log(buf.readUInt32LE(4).toString(16));

Output:

  <Buffer 21 09 19 98 16 09 19 96>  98190921  16981909  9169819  19091698  96190916

Example 2:

javascript

// Node program to demonstrate the   // Buffer.readUInt32LE() Method   // Allocating buffer from array const buf = Buffer.from([0x21, 0x09, 0x19, 0x98,                      0x34, 0xae, 0xe8, 0xff]);  // Printing allocated buffer console.log(buf);   // Reading 16bits data from the buffer // and printing it as a string console.log(buf.readUInt32LE(0).toString(16)); console.log(buf.readUInt32BE(0).toString(16)); console.log(buf.readUInt32LE(1).toString(16)); console.log(buf.readUInt32BE(1).toString(16)); console.log(buf.readUInt32LE(2).toString(16)); console.log(buf.readUInt32BE(2).toString(16)); console.log(buf.readUInt32LE(3).toString(16)); console.log(buf.readUInt32BE(3).toString(16)); console.log(buf.readUInt32LE(4).toString(16)); console.log(buf.readUInt32BE(4).toString(16));

Output:

  <Buffer 21 09 19 98 34 ae e8 ff>  98190921  21091998  34981909  9199834  ae349819  199834ae  e8ae3498  9834aee8  ffe8ae34  34aee8ff

Example 3:

javascript

// Node program to demonstrate the   // Buffer.readUInt32LE() 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.readUInt32LE(0).toString(16));   // Wrong index is provoded to produce error console.log(buf.readUInt32LE(1).toString(16));

Output:

  <Buffer 21 09 19 98>  98190921  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 <= 0. Received 1      at boundsError (internal/buffer.js:49:9)      at Buffer.readUInt32LE (internal/buffer.js:105:5)      at Object. (C:\nodejs\buf_readuint32le_2.js:10:17)      . . .

Note: The above program will compile and run by using the node index.js command. Reference: https://nodejs.org/api/buffer.html#buffer_buf_readuint32le_offset