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Node.js Buffer.writeBigUInt64LE() Method

Last Updated : 07 Jul, 2020
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The Buffer.writeBigUInt64LE() method is an inbuilt application programming interface of class Buffer within the Buffer module which is used to writes little endian 64-bits Big integer value to an allocated buffer at the specified offset.

Syntax:

Buffer.writeBigUInt64LE( value, offset )

Parameters:

  • value: This parameter specifies 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 value is anything other than this.
  • offset: It specifies the number of bytes to skip before write 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 unsigned integer value that is the sum of offset and number of bytes written.

    Below examples illustrate the use of Buffer.writeBigUInt64LE() method in Node.js:

    Example 1:
    Filename: index.js




    // Node.js program to demonstrate the
    // buffer.writeBigUInt64LE() method 
    const buf = Buffer.allocUnsafe(8);
      
    // Writing big integer value into buffer
    // by using writeBigUInt64LE() method
    buf.writeBigUInt64LE(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




    // Node.js program to demonstrate the
    // buffer.writeBigUInt64LE() method 
    const buf = Buffer.allocUnsafe(8);
      
    // writing big integer value into buffer
    // by using writeBigUInt64LE() method
    buf.writeBigUInt64LE(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_writebiguint64le_value_offset


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