Naughty Program Manipulator
    Have ideas to improve npm?Join in the discussion! »

    xss
    TypeScript icon, indicating that this package has built-in type declarations

    1.0.9 • Public • Published

    NPM version Node.js CI Test coverage David deps node version npm download npm license

    Sanitize untrusted HTML (to prevent XSS) with a configuration specified by a Whitelist.

    Greenkeeper badge

    xss


    xss is a module used to filter input from users to prevent XSS attacks. (What is XSS attack?)

    Project Homepage: http://jsxss.com

    Try Online: http://jsxss.com/en/try.html

    中文版文档


    Features

    • Specifies HTML tags and their attributes allowed with whitelist
    • Handle any tags or attributes using custom function.

    Reference

    Benchmark (for references only)

    • the xss module: 22.53 MB/s
    • xss() function from module validator@0.3.7: 6.9 MB/s

    For test code please refer to benchmark directory.

    They are using xss module

    Install

    NPM

    npm install xss

    Bower

    bower install xss

    Or

    bower install https://github.com/leizongmin/js-xss.git

    Usages

    On Node.js

    var xss = require("xss");
    var html = xss('<script>alert("xss");</script>');
    console.log(html);

    On Browser

    Shim mode (reference file test/test.html):

    <script src="https://rawgit.com/leizongmin/js-xss/master/dist/xss.js"></script>
    <script>
      // apply function filterXSS in the same way
      var html = filterXSS('<script>alert("xss");</scr' + "ipt>");
      alert(html);
    </script>

    AMD mode - shim:

    <script>
      require.config({
        baseUrl: "./",
        paths: {
          xss: "https://rawgit.com/leizongmin/js-xss/master/dist/xss.js",
        },
        shim: {
          xss: { exports: "filterXSS" },
        },
      });
      require(["xss"], function (xss) {
        var html = xss('<script>alert("xss");</scr' + "ipt>");
        alert(html);
      });
    </script>

    Notes: please don't use the URL https://rawgit.com/leizongmin/js-xss/master/dist/xss.js in production environment.

    Command Line Tool

    Process File

    You can use the xss command line tool to process a file. Usage:

    xss -i <input_file> -o <output_file>

    Example:

    xss -i origin.html -o target.html

    Active Test

    Run the following command, them you can type HTML code in the command-line, and check the filtered output:

    xss -t

    For more details, please run $ xss -h to see it.

    Custom filter rules

    When using the xss() function, the second parameter could be used to specify custom rules:

    options = {}; // Custom rules
    html = xss('<script>alert("xss");</script>', options);

    To avoid passing options every time, you can also do it in a faster way by creating a FilterXSS instance:

    options = {}; // Custom rules
    myxss = new xss.FilterXSS(options);
    // then apply myxss.process()
    html = myxss.process('<script>alert("xss");</script>');

    Details of parameters in options would be described below.

    Whitelist

    By specifying a whiteList, e.g. { 'tagName': [ 'attr-1', 'attr-2' ] }. Tags and attributes not in the whitelist would be filter out. For example:

    // only tag a and its attributes href, title, target are allowed
    var options = {
      whiteList: {
        a: ["href", "title", "target"],
      },
    };
    // With the configuration specified above, the following HTML:
    // <a href="#" onclick="hello()"><i>Hello</i></a>
    // would become:
    // <a href="#">&lt;i&gt;Hello&lt;/i&gt;</a>

    For the default whitelist, please refer xss.whiteList.

    Customize the handler function for matched tags

    By specifying the handler function with onTag:

    function onTag(tag, html, options) {
      // tag is the name of current tag, e.g. 'a' for tag <a>
      // html is the HTML of this tag, e.g. '<a>' for tag <a>
      // options is some addition informations:
      //   isWhite    boolean, whether the tag is in whitelist
      //   isClosing  boolean, whether the tag is a closing tag, e.g. true for </a>
      //   position        integer, the position of the tag in output result
      //   sourcePosition  integer, the position of the tag in input HTML source
      // If a string is returned, the current tag would be replaced with the string
      // If return nothing, the default measure would be taken:
      //   If in whitelist: filter attributes using onTagAttr, as described below
      //   If not in whitelist: handle by onIgnoreTag, as described below
    }

    Customize the handler function for attributes of matched tags

    By specifying the handler function with onTagAttr:

    function onTagAttr(tag, name, value, isWhiteAttr) {
      // tag is the name of current tag, e.g. 'a' for tag <a>
      // name is the name of current attribute, e.g. 'href' for href="#"
      // isWhiteAttr whether the attribute is in whitelist
      // If a string is returned, the attribute would be replaced with the string
      // If return nothing, the default measure would be taken:
      //   If in whitelist: filter the value using safeAttrValue as described below
      //   If not in whitelist: handle by onIgnoreTagAttr, as described below
    }

    Customize the handler function for tags not in the whitelist

    By specifying the handler function with onIgnoreTag:

    function onIgnoreTag(tag, html, options) {
      // Parameters are the same with onTag
      // If a string is returned, the tag would be replaced with the string
      // If return nothing, the default measure would be taken (specifies using
      // escape, as described below)
    }

    Customize the handler function for attributes not in the whitelist

    By specifying the handler function with onIgnoreTagAttr:

    function onIgnoreTagAttr(tag, name, value, isWhiteAttr) {
      // Parameters are the same with onTagAttr
      // If a string is returned, the value would be replaced with this string
      // If return nothing, then keep default (remove the attribute)
    }

    Customize escaping function for HTML

    By specifying the handler function with escapeHtml. Following is the default function (Modification is not recommended):

    function escapeHtml(html) {
      return html.replace(/</g, "&lt;").replace(/>/g, "&gt;");
    }

    Customize escaping function for value of attributes

    By specifying the handler function with safeAttrValue:

    function safeAttrValue(tag, name, value) {
      // Parameters are the same with onTagAttr (without options)
      // Return the value as a string
    }

    Customize CSS filter

    If you allow the attribute style, the value will be processed by cssfilter module. The cssfilter module includes a default css whitelist. You can specify the options for cssfilter module like this:

    myxss = new xss.FilterXSS({
      css: {
        whiteList: {
          position: /^fixed|relative$/,
          top: true,
          left: true,
        },
      },
    });
    html = myxss.process('<script>alert("xss");</script>');

    If you don't want to filter out the style content, just specify false to the css option:

    myxss = new xss.FilterXSS({
      css: false,
    });

    For more help, please see https://github.com/leizongmin/js-css-filter

    Quick Start

    Filter out tags not in the whitelist

    By using stripIgnoreTag parameter:

    • true filter out tags not in the whitelist
    • false: by default: escape the tag using configured escape function

    Example:

    If stripIgnoreTag = true is set, the following code:

    code:
    <script>
      alert(/xss/);
    </script>

    would output filtered:

    code:alert(/xss/);

    Filter out tags and tag bodies not in the whitelist

    By using stripIgnoreTagBody parameter:

    • false|null|undefined by default: do nothing
    • '*'|true: filter out all tags not in the whitelist
    • ['tag1', 'tag2']: filter out only specified tags not in the whitelist

    Example:

    If stripIgnoreTagBody = ['script'] is set, the following code:

    code:
    <script>
      alert(/xss/);
    </script>

    would output filtered:

    code:

    Filter out HTML comments

    By using allowCommentTag parameter:

    • true: do nothing
    • false by default: filter out HTML comments

    Example:

    If allowCommentTag = false is set, the following code:

    code:<!-- something -->
    END

    would output filtered:

    code: END

    Examples

    Allow attributes of whitelist tags start with data-

    var source = '<div a="1" b="2" data-a="3" data-b="4">hello</div>';
    var html = xss(source, {
      onIgnoreTagAttr: function (tag, name, value, isWhiteAttr) {
        if (name.substr(0, 5) === "data-") {
          // escape its value using built-in escapeAttrValue function
          return name + '="' + xss.escapeAttrValue(value) + '"';
        }
      },
    });
    
    console.log("%s\nconvert to:\n%s", source, html);

    Result:

    <div a="1" b="2" data-a="3" data-b="4">hello</div>
    convert to:
    <div data-a="3" data-b="4">hello</div>

    Allow tags start with x-

    var source = "<x><x-1>he<x-2 checked></x-2>wwww</x-1><a>";
    var html = xss(source, {
      onIgnoreTag: function (tag, html, options) {
        if (tag.substr(0, 2) === "x-") {
          // do not filter its attributes
          return html;
        }
      },
    });
    
    console.log("%s\nconvert to:\n%s", source, html);

    Result:

    <x
      ><x-1>he<x-2 checked></x-2>wwww</x-1
      ><a>
        convert to: &lt;x&gt;<x-1>he<x-2 checked></x-2>wwww</x-1><a></a></a
    ></x>

    Parse images in HTML

    var source =
      '<img src="img1">a<img src="img2">b<img src="img3">c<img src="img4">d';
    var list = [];
    var html = xss(source, {
      onTagAttr: function (tag, name, value, isWhiteAttr) {
        if (tag === "img" && name === "src") {
          // Use the built-in friendlyAttrValue function to escape attribute
          // values. It supports converting entity tags such as &lt; to printable
          // characters such as <
          list.push(xss.friendlyAttrValue(value));
        }
        // Return nothing, means keep the default handling measure
      },
    });
    
    console.log("image list:\n%s", list.join(", "));

    Result:

    image list: img1, img2, img3, img4

    Filter out HTML tags (keeps only plain text)

    var source = "<strong>hello</strong><script>alert(/xss/);</script>end";
    var html = xss(source, {
      whiteList: {}, // empty, means filter out all tags
      stripIgnoreTag: true, // filter out all HTML not in the whitelist
      stripIgnoreTagBody: ["script"], // the script tag is a special case, we need
      // to filter out its content
    });
    
    console.log("text: %s", html);

    Result:

    text: helloend

    License

    Copyright (c) 2012-2018 Zongmin Lei(雷宗民) <leizongmin@gmail.com>
    http://ucdok.com
    
    The MIT License
    
    Permission is hereby granted, free of charge, to any person obtaining
    a copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:
    
    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.
    
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
    LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    

    Install

    npm i xss

    DownloadsWeekly Downloads

    1,372,921

    Version

    1.0.9

    License

    MIT

    Unpacked Size

    142 kB

    Total Files

    16

    Last publish

    Collaborators

    • avatar