nodejs buffer to number

Nodejs is a very powerful back-end JavaScript solution that has been widely used in server-side programming. The Buffer type is also one of the important features of Nodejs.

In Nodejs, the Buffer object is mainly used to process binary data, so it is usually used in scenarios such as network communication and data persistence (such as file reading and writing).

In actual work, we often encounter scenarios where we need to convert a Buffer type data into a numerical type in JavaScript, so this article will introduce the solution to this problem.

1. Process Buffer into decimal numbers

In Nodejs, it is very easy to convert a binary data into a decimal number. You only need to use the readInt method of the Buffer class. Can. Parameters supported by the readInt method include the number of bytes, offset and whether to use unsigned integers.

For example, for an 8-byte Buffer type data, you can use the following statement to convert it into a decimal number:

let buffer = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF]); 
let number = buffer.readIntBE(0, 8); 
console.log(number); //输出为78187493520

In the above code, the Buffer.from method is used to convert a length of 8 A Buffer object of bytes is created. Then use the readIntBE method to process it into a decimal number.

2. Process Buffer into hexadecimal numbers

In addition to processing a Buffer data into decimal numbers, you can also process it into hexadecimal numbers number. This can be achieved through the toString method that comes with Nodejs.

let buffer = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF]); 
let hex = buffer.toString('hex');
console.log(hex); // 输出为：1234567890abcdef

3. Processing big-endian and little-endian order

It should be noted that when processing Buffer objects as numbers, the byte order of the data needs to be considered. Normally, we need to determine the byte order of the data based on the source and usage needs of the data.

In Nodejs, you can use the common BE and LE methods to determine the byte order. BE refers to big endian order, and LE refers to little endian order.

BE: Store data in order from high byte to low byte, that is, high byte first and low byte last.
LE: Store data in order from low byte to high byte, that is, low byte first and high byte last.

For example, for a 2-byte Buffer data, one is BE and the other is LE:

let BE_Buffer = Buffer.from([0x12, 0x34]);
let LE_Buffer = Buffer.from([0x34, 0x12]);

console.log(BE_Buffer.readIntBE(0, 2)); // 输出为： 4660
console.log(BE_Buffer.readUIntBE(0, 2)); // 输出为： 4660

console.log(LE_Buffer.readIntLE(0, 2)); // 输出为： 4660
console.log(LE_Buffer.readUIntLE(0, 2)); // 输出为： 4660

4. Summary

Convert a Buffer type Converting data to numeric types in JavaScript is one of the commonly used operations in Nodejs. By using different decoding methods, the byte order, big and small endianness and other attributes of the data can be correctly identified and converted into numbers, ensuring the correctness of the data during transmission, saving, reading, etc.

The above is the method of converting the Buffer type into a numeric type in Nodejs introduced in this article. I hope it can be helpful to everyone.

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