https://github.com/idan-at/native-sizeof
A native package to quickly calculate a JS object size
https://github.com/idan-at/native-sizeof
javascript memory rust size-calculation typescript
Last synced: 3 months ago
JSON representation
A native package to quickly calculate a JS object size
- Host: GitHub
- URL: https://github.com/idan-at/native-sizeof
- Owner: idan-at
- Created: 2021-05-19T13:24:09.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2022-01-26T14:04:21.000Z (over 4 years ago)
- Last Synced: 2025-09-14T14:20:41.594Z (9 months ago)
- Topics: javascript, memory, rust, size-calculation, typescript
- Language: JavaScript
- Homepage:
- Size: 238 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# native-sizeof
[](https://badge.fury.io/js/native-sizeof)
[](https://github.com/idan-at/native-sizeof/actions?query=workflow%3A"test")
A native package to quickly calculate an object size, written in Rust.
## Installation
`npm install --save native-sizeof`
## Usage
```js
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](https://tc39.es/ecma262/):
- 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.