safely-set-inner-html

Keep calm and don't use dangerouslySetInnerHTML anymore

• Presentation
• Getting started
• Usage
  • Cache
  • Server-side rendering
  • Blacklist warnings
• Live demo
• Configuration
• Feedbacks

🤔 Presentation

This library for React has a very simple goal: prevent the use of dangerouslySetInnerHTML function.

A typical use case is when you are working on a multi language project and there is html in your bundle values !

{
    "article.cite": "About the <a href=\"http://example.com\">Author !</a>"
}

🚨 Actually the only way to keep this HTML tag is the use of dangerouslySetInnerHTML but it presents a high security risk and the team actually warns you about it: read this to know more

😇 safelySetInnerHTML will solve this issue by filtering and creating automatically the react dom and return it to your component.

By default, only few tags are allowed so you don't need to sanitize the HTML string yourself, just configure the scope for your needs.

Default config

{
  ALLOWED_TAGS: [
    'strong',
    'a'
  ],
  ALLOWED_ATTRIBUTES: [
    'href'
  ],
  KEY_NAME: 'ssih-tag-'
}

ALLOWED_TAGS

• Type: (array)
• Description: This is the whitelist of tags that will be rendered in ReactDOM. At runtime, if a desired tag is not in this list, it won't generate a React element but return its content directly.

ALLOWED_ATTRIBUTES

• Type: (array)
• Description: This is the whitelist of allowed attributes for each rendered tag. At runtime, if a desired attribute is not in this list, it won't be applied to the generated React element.

KEY_NAME

• Type: (string)
• Description: This is the prefix that will be added to each key property of React.

📥 Getting started

Install the library with npm:

$ npm install -P safely-set-inner-html

🔌 Usage

import React from 'react';
+ import SafelySetInnerHTML from 'safely-set-inner-html';
 
+ const instance = new SafelySetInnerHTML();
 
export default class extends React.Component {
  render() {
    return (
      <article>
        <h2>{this.props.title}</h2>
-       <p dangerouslySetInnerHTML={{ __html: this.props.content }} />
+       <p>{instance.transform(this.props.content)}</p>
      </article>
    );
  }
}

Cache

Note that safely-set-inner-html is caching automatically the generated dom each time the transform function is called. So don't be afraid of any re-rendering call, the cache will be retrieved from the given string.

It is a simple javascript Object which belongs to the current instance, you can view it like this if needed:

import SafelySetInnerHTML from 'safely-set-inner-html';
 
const instance = new SafelySetInnerHTML();
 
instance.transform('Hello <strong>Cache !</strong>');
console.log(instance.cache);
 
// [{
//   str: 'Hello <strong>Cache !</strong>',
//   dom: [ 'Hello ', [Object] ]
// }]

The cached dom will always be returned if a cache entry is found.

Server-side rendering

Note that as safely-set-inner-html is using only React.createElement, it will work perfectly with Server-side rendered APP 👍

Blacklist warnings

In order to help you preventing any potential attack, a check is done each time an attribute or a tag is created. If the tag or the attribute is contained inside this list, it will log a warning in your console.

e.g.

// Be careful with the use of attribute ontransitionend, it presents a potential XSS risk

🕹 Live demo

You can play with this example on codesandbox

🔧 Configuration

Here is a recommended way of configuring SafelySetInnerHTML:

// mySafelySetInnerHTML.js
import SafelySetInnerHTML from 'safely-set-inner-html';
 
const mySafelySetInnerHTML = new SafelySetInnerHTML({
  ALLOWED_TAGS: [
    'a',
    'strong'
  ],
  ALLOWED_ATTRIBUTES: [
    'href',
    'class'
  ]
});
 
export default mySafelySetInnerHTML.transform;

And just use it like this inside your project:

// myComponent.js
import React from 'react';
import safelySetInnerHTML from './mySafelySetInnerHTML';
 
const MyComponent = ({ HTMLContent }) => (
  <p>{safelySetInnerHTML(HTMLContent)}</p>
);

Feedbacks

As this library is young, I would appreciate any feedbacks about it and if you need specific features do not hesitate to create an issue !

Thank you ! 🎷