Node.js Buffer.writeBigInt64LE() Method

The Buffer.writeBigInt64LE() method is an inbuilt application programming interface of class Buffer within the Buffer module which is used to write little-endian 64-bit Big integer value to an allocated buffer at the specified offset.

Syntax:

Buffer.writeBigInt64LE( value, offset )

Parameters: This method accepts two parameters as mentioned above and described below:

• value: This parameter specifies a big integer value to be written to the buffer. It should be a valid 64 bits little endian Big integer value. Behavior is undefined when the value is anything other than this.
• offset: It specifies the number of bytes to skip before writing or simply signify the index in the buffer. The value of offset lies 0 <= offset <= Buffer.length – 8. Its default value is 0.

Return Value: This method returns an integer value that is the sum of offset and number of bytes written. 

The below examples illustrate the use of the Buffer.writeBigInt64LE() method in Node.js: 

Example 1:

Filename: index.js

javascript

// Node.js program to demonstrate the
// buffer.writeBigInt64lE() method
const buf = Buffer.allocUnsafe(8);

// Writing big integer value into buffer
// by using writeBigInt64LE() method
buf.writeBigInt64LE(0x01030405060708n, 0);

// Display the buffer
console.log(buf);

Run the index.js file using the following command:

node index.js

Output:

<Buffer 08 07 06 05 04 03 01 00>

Example 2: Filename: index.js

javascript

// Node.js program to demonstrate the
// buffer.writeBigInt64lE() method
const buf = Buffer.allocUnsafe(8);

// Writing big integer value into buffer
// by using writeBigInt64LE() method
buf.writeBigInt64LE(0xaa03040506efffn, 0);

// Display the buffer
console.log(buf);

Run the index.js file using the following command:

node index.js

Output:

<Buffer ff ef 06 05 04 03 aa 00>

Reference: https://nodejs.org/dist/latest-v12.x/docs/api/buffer.html#buffer_buf_writebigint64le_value_offset

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