native-sizeof

A native package to quickly calculate an object size, written in Rust.

Installation

npm install --save native-sizeof

Usage

const { sizeof } = require('native-sizeof');

const object = {
  'key': 'value'
}

sizeof(object); // returns the size of the object (8 character => 2 * 8 = 16)
sizeof("hello"); // 5 * 2 = 10
sizeof(123) // 8 for a number
sizeof(true) // 2 for a boolean

sizeof(null) // 0 for null, undefined

Summary

In javascript, there is no manual memory management, and therefore no sizeof capabilities, unlike C and other system languages.

However, sometimes it is useful to know how much size your object takes, so it will provide an approximation of how much memory is confused by your app, and how much memory is actually needed by your VM / Container.

Since iterating over an object and summing up the occupied memory is a synchronous task, which blocks the main thread, this library is written in Rust for better performance.

Object size calculation

According to the ECMAScript® Language Specification:

• Each boolean value is represented using 2 bytes.
• Each number value is represented using 8 bytes.
• Each string value is represented using 2 bytes per character. (so a string of length 3 takes 2 * 3 = 6 bytes).

NOTE: Some JS engines might optimize those numbers, but those are a good upper bound.

Development

Prerequisites

• Node (at least 12)
• Rust (stable)

Building

• npm install

This will install the relevant development packages from npm and will build the binary from the rust code.

Testing

• npm test

This runs both Rust tests and JS integration tests.