Buffer.includes() Method in Node.js

Buffers in Node.js are used for handling binary data directly in memory, making them crucial for low-level I/O tasks. Among the many useful methods provided by the Buffer class, includes() helps determine whether a particular sequence of bytes exists within the buffer. In this blog, we’ll explore how Buffer.includes() works and when to use it.

What is Buffer.includes()?

The Buffer.includes() method checks whether the buffer contains a specified value. This is similar to the includes() method for arrays and strings, but it operates at the byte level within a buffer.

Syntax of Buffer.includes()

The general syntax for the method is:

buffer.includes(value, byteOffset, encoding)

• value: The value to search for. It can be a number, string, or another buffer.
• byteOffset (optional): The position in the buffer to begin the search. Defaults to 0.
• encoding (optional): The character encoding to use if the value is a string. Defaults to 'utf8'.

Simple Example

Here’s a basic example of how you can use Buffer.includes() to check for a substring within a buffer:

const buffer = Buffer.from('Node.js Buffers');

console.log(buffer.includes('Buffers'));  // true
console.log(buffer.includes('JavaScript'));  // false

The first call returns true because the string "Buffers" exists in the buffer. The second returns false since "JavaScript" does not.

Using Byte Offset

You can start your search from a specific byte offset using the second parameter:

const buffer = Buffer.from('Welcome to Node.js');

console.log(buffer.includes('Welcome', 8)); // false
console.log(buffer.includes('Node', 11));   // true

In the first check, "Welcome" does not occur after byte 8, so the result is false. The second check successfully finds "Node" starting at index 11.

Searching with Buffers and Numbers

You can also search using another buffer or a single byte number:

const mainBuffer = Buffer.from([10, 20, 30, 40, 50]);

console.log(mainBuffer.includes(Buffer.from([30, 40]))); // true
console.log(mainBuffer.includes(20));                    // true

Both methods work perfectly. In the first case, we look for a sequence of bytes. In the second, we search for a single byte value.

Case Sensitivity

Keep in mind that Buffer.includes() is case-sensitive when working with strings:

const buffer = Buffer.from('Buffer Example');

console.log(buffer.includes('example'));  // false
console.log(buffer.includes('Example'));  // true

When to Use Buffer.includes()

• To validate binary input data quickly
• For searching specific byte patterns in files or network streams
• When working with custom binary protocols or buffers

Conclusion

The Buffer.includes() method is a simple yet powerful utility when working with binary data in Node.js. It allows you to determine if a buffer contains specific data, whether as a string, number, or another buffer. With options for specifying offset and encoding, it gives you flexible control over your data validation and search operations.