insane

Lean and configurable whitelist-oriented HTML sanitizer

Works well in browsers, as its footprint size is very small (around ~2kb gzipped). API inspired by sanitize-html (which is around 100kb gzipped).

_{You would be insane not to use this!}

Install

npm install insane --save

Usage

insane('<div>foo<span>bar</span></div>', { allowedTags: ['div'] })
// <- '<div>foo</div>'

Contrary to similar sanitizers, insane drops the whole tree of descendants for elements that aren't allowed tags.

API

insane(html, options?, strict?)

• html can be an arbitrary HTML string
• options are detailed below
• strict means that options won't be based off of insane.defaults if set to true

The parser takes into account that some elements can be self-closing. For safety reasons the sanitizer will only accept a valid URL for background, base, cite, href, longdesc, src, and usemap elements. "Valid URL" means that it begins with either #, /, or any of options.allowedSchemes (followed by :).

options

Sensible defaults are provided. You can override specific options as needed.

allowedSchemes

Defaults to ['http', 'https', 'mailto'].

allowedTags

An array of tags that you'll allow in the resulting HTML.

Example

Only allow spans, discarding the rest of elements.

insane('<div>foo</div><span>bar</span>', {
  allowedTags: ['span']
});
// <- '<span>bar</span>'

allowedAttributes

An object describing the attributes you'll allow for each individual tag name.

Example

Only allow spans, and only allow those spans to have an id (discarding the rest of their attributes).

insane('<span id="bar" class="super">bar</span>', {
  allowedTags: ['span'],
  allowedAttributes: { span: ['id'] }
});
// <- '<span id="bar">bar</span>'

allowedClasses

If 'class' is listed as an allowed attribute, every single class will be allowed. If you don't list 'class' as an allowed attribute, you can provide a class whitelist per tag name.

Example

Only allow spans to have super or bad class names, discarding the rest of them.

insane('<span class="super mean and bad">bar</span>', {
  allowedTags: ['span'],
  allowedClasses: { span: ['super', 'bad'] }
});
// <- '<span class="super bad">bar</span>'

filter

Takes a function(token) that allows you to do additional validation beyond exact tag name and attribute matching. The token object passed to your filter contains the following properties.

• tag is the lowercase tag name of the element
• attrs is an object containing every attribute in the element, including those that may not be in the whitelist

If you return a falsy value the element and all of its descendants will not be included in the output. Note that you are allowed to change the attrs, and even add new ones, transforming the output.

Example

Require that <span> elements have an aria-label value.

function filter (token) {
  return token.tag !== 'span' || token.attrs['aria-label'];
}
insane('<span aria-label="a foo">foo</span><span>bar</span>', {
  allowedTags: ['span'],
  allowedAttributes: { span: ['aria-label'] },
  filter: filter
});
// <- '<span aria-label="a foo">foo</span>'

transformText

Takes a function(text) that allows you to modify text content in HTML elements. Runs for every piece of text content. The returned value is used instead of the original text contents.

Defaults

The default configuration is used if you don't provide any. This object is available at insane.defaults. You are free to manipulate the defaults themselves.

{
  "allowedAttributes": {
    "a": ["href", "name", "target"],
    "iframe": ["allowfullscreen", "frameborder", "src"],
    "img": ["src"]
  },
  "allowedClasses": {},
  "allowedSchemes": ["http", "https", "mailto"],
  "allowedTags": [
    "a", "article", "b", "blockquote", "br", "caption", "code", "del", "details", "div", "em",
    "h1", "h2", "h3", "h4", "h5", "h6", "hr", "i", "img", "ins", "kbd", "li", "main", "ol",
    "p", "pre", "section", "span", "strike", "strong", "sub", "summary", "sup", "table",
    "tbody", "td", "th", "thead", "tr", "u", "ul"
  ],
  "filter": null,
  "transformText": null
}

License

MIT

• Add 'u' tag to accepted whitelist.

2.5.1 Self-Filter

• Filter works properly with self-closing tags

2.5.0 Transformers

• Added transformText option allowing to mangle or fork content of text nodes

2.4.3 Abbreviate!

• Added abbr tag name to defaults

2.4.2 Mark

• Added mark tag name to defaults

2.4.1 Encore

• Fix encoding issues in text nodes, which would become decoded and re-encoded for no reason

2.4.0 Thoughtseize

• Instead of throwing an exception, discards unclosed HTML tags at the end of the input stream

2.3.0 Implosion

• Attributes without a value are preserved as-is

2.2.0 Big Bang

• Attributes without a value, such as <button disabled></button> are translated into their better compatible counterparts <button disabled="disabled"></button>

2.1.1 Assignments

• Moved assign() into assignment npm module

2.1.0 Label Maker

• Added title, and aria-label to the a attribute whitelist
• Added title, aria-label, and alt to the img attribute whitelist

2.0.0 Sane Defaults

• Sanitizer options are now always based off of defaults
• Added strict parameter to revert to 1.0.0 behavior
• Removed iframe from default allowedTags collection
• Allow relative URLs such as images/deep.png in attributes
• Significantly sped up tag-intensive HTML parsing

1.0.0 IPO

• Initial Public Release