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https://github.com/nuxt-contrib/devalue
Gets the job done when JSON.stringify can't
https://github.com/nuxt-contrib/devalue
Last synced: 4 months ago
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Gets the job done when JSON.stringify can't
- Host: GitHub
- URL: https://github.com/nuxt-contrib/devalue
- Owner: nuxt-contrib
- License: mit
- Fork: true (Rich-Harris/devalue)
- Created: 2018-10-03T12:14:58.000Z (over 6 years ago)
- Default Branch: main
- Last Pushed: 2023-05-02T20:03:58.000Z (almost 2 years ago)
- Last Synced: 2024-04-23T23:20:51.662Z (10 months ago)
- Language: TypeScript
- Homepage: https://npm.runkit.com/devalue
- Size: 348 KB
- Stars: 75
- Watchers: 7
- Forks: 9
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# @nuxt/devalue
[![npm version][npm-version-src]][npm-version-href]
[![npm downloads][npm-downloads-src]][npm-downloads-href]
[![codecov][codecov-src]][codecov-href]
[![package phobia][package-phobia-src]][package-phobia-href]
[![bundle phobia][bundle-phobia-src]][bundle-phobia-href]
> Forked from [devalue](https://github.com/Rich-Harris/devalue) to log errors on non-serializable properties rather than throwing `Error`.
Like `JSON.stringify`, but handles
* cyclical references (`obj.self = obj`)
* repeated references (`[value, value]`)
* `undefined`, `Infinity`, `NaN`, `-0`
* regular expressions
* dates
* `Map` and `Set`
* `.toJSON()` method for non-POJOs
Try it out on [runkit.com](https://npm.runkit.com/@nuxt/devalue).
## Goals:
* Performance
* Security (see [XSS mitigation](#xss-mitigation))
* Compact output
## Non-goals:
* Human-readable output
* Stringifying functions or arbritary non-POJOs
## Usage
```js
import devalue from '@nuxt/devalue';
let obj = { a: 1, b: 2 };
obj.c = 3;
devalue(obj); // '{a:1,b:2,c:3}'
obj.self = obj;
devalue(obj); // '(function(a){a.a=1;a.b=2;a.c=3;a.self=a;return a}({}))'
```
If `devalue` encounters a function or a non-POJO, it will throw an error.
## XSS mitigation
Say you're server-rendering a page and want to serialize some state, which could include user input. `JSON.stringify` doesn't protect against XSS attacks:
```js
const state = {
userinput: ``
};
const template = `
<script>
// NEVER DO THIS
var preloaded = ${JSON.stringify(state)};
`;
```
Which would result in this:
```html
// NEVER DO THIS
var preloaded = {"userinput":""};
```
Using `devalue`, we're protected against that attack:
```js
const template = `
var preloaded = ${devalue(state)};
`;
```
```html
var preloaded = {userinput:"\\u003C\\u002Fscript\\u003E\\u003Cscript src=\'https:\\u002F\\u002Fevil.com\\u002Fmwahaha.js\'\\u003E"};
```
This, along with the fact that `devalue` bails on functions and non-POJOs, stops attackers from executing arbitrary code. Strings generated by `devalue` can be safely deserialized with `eval` or `new Function`:
```js
const value = (0,eval)('(' + str + ')');
```
## Other security considerations
While `devalue` prevents the XSS vulnerability shown above, meaning you can use it to send data from server to client, **you should not send user data from client to server** using the same method. Since it has to be evaluated, an attacker that successfully submitted data that bypassed `devalue` would have access to your system.
When using `eval`, ensure that you call it *indirectly* so that the evaluated code doesn't have access to the surrounding scope:
```js
{
const sensitiveData = 'Setec Astronomy';
eval('sendToEvilServer(sensitiveData)'); // pwned :(
(0,eval)('sendToEvilServer(sensitiveData)'); // nice try, evildoer!
}
```
Using `new Function(code)` is akin to using indirect eval.
## See also
* [lave](https://github.com/jed/lave) by Jed Schmidt
* [arson](https://github.com/benjamn/arson) by Ben Newman
* [tosource](https://github.com/marcello3d/node-tosource) by Marcello Bastéa-Forte
* [serialize-javascript](https://github.com/yahoo/serialize-javascript) by Eric Ferraiuolo
## License
[MIT](LICENSE)
[npm-version-src]: https://flat.badgen.net/npm/v/@nuxt/devalue/latest
[npm-version-href]: https://www.npmjs.com/package/@nuxt/devalue
[npm-downloads-src]: https://flat.badgen.net/npm/dm/@nuxt/devalue
[npm-downloads-href]: https://www.npmjs.com/package/@nuxt/devalue
[circleci-src]: https://flat.badgen.net/circleci/github/nuxt-contrib/devalue
[circleci-href]: https://circleci.com/gh/nuxt-contrib/devalue
[package-phobia-src]: https://flat.badgen.net/packagephobia/install/@nuxt/devalue
[package-phobia-href]: https://packagephobia.now.sh/result?p=@nuxt/devalue
[bundle-phobia-src]: https://flat.badgen.net/bundlephobia/minzip/@nuxt/devalue
[bundle-phobia-href]: https://bundlephobia.com/result?p=@nuxt/devalue
[codecov-src]: https://flat.badgen.net/codecov/c/github/nuxt-contrib/devalue/master
[codecov-href]: https://codecov.io/gh/nuxt-contrib/devalue