jstoxml

Convert JavaScript objects (and JSON) to XML (for RSS, Podcasts, etc.)

Everyone loves JSON, and more and more folks want to move that direction, but we still need things outputted in XML! Particularly for RSS feeds and Podcasts.

This is inspired by node-jsontoxml, which was found to be a bit too rough around the edges. jstoxml attempts to fix that by being more flexible.

Installation

• npm install jstoxml

Simple example

import { toXML } from 'jstoxml';

// toXML(content, config)
const content = {
    a: {
        foo: 'bar'
    }
};
const config = {
    indent: '    '
};

toXML(content, config);
/*
Output:
`<a>
    bar
</a>`
*/

Configuration object options (passed as second parameter to toXML())

Key name	Type	Default	Description
indent	string		Indent string, repeated n times (where n=tree depth).
header	string, boolean		Outputs a simple XML 1.0 UTF-8 header when true. Can also be set to a custom string.
attributeReplacements	object	{ "&lt;": "&lt;", "&gt;": "&gt;", "&amp;": "&amp;", "\"": """ }	XML attribute value substrings to replace (e.g. <a>). Does not double encode HTML entities (e.g. &lt; is preserved and NOT converted to &amp;lt).
attributeFilter	function		Filters out attributes based on user-supplied function.
attributeExplicitTrue	boolean	false	When true explicitly outputs true attribute value strings, e.g. </a><a> instead of </a><a>.
contentMap	function		Custom map function to transform XML content. Runs after contentReplacements.
contentReplacements	object	{ "&lt;": "&lt;", "&gt;": "&gt;", "&amp;": "&amp;", "\"": """ }	XML content strings to replace (e.g. </a><a>This &amp; that</a> becomes <a>This &amp; that</a>).
selfCloseTags	boolean	true	Whether tags should be self-closing.

Changelog

Version 3.2.0

• new config option selfCloseTags added which is used as an easier global setting to enable/disable self-closing tags.

Version 3.1.0

• config option contentMap can now be passed to transform any XML content. For instance, if you want <a>null</a> to instead appear as <a></a> you pass in contentMap: (content) => { return content === null ? '' : content }
• fixed an issue with improper line breaks and indenting with null content

Version 3.0.0

• BREAKING CHANGE: config option attributesFilter has been renamed attributeReplacements
• BREAKING CHANGE: config option filter has been renamed contentReplacements
• CDATA blocks are now untouched (no HTML entity replacements) and unindented (#56)
• true attribute values can now be outputted by setting config option attributeExplicitTrue: true (#57)
• attributes can now be filtered out by supplying a custom function to the new config option attributeFilter. For instance, to remove null attribute values from the output, you can supply the config option attributeFilter: (key, val) => val === null (#58 and #10)
• devDependencies: migrated from babel-eslint to @babel/eslint-parser, migrated from uglify-es to uglify-js

Version 2.2.0

• Initial support for XML comments (#47)

Version 2.1.1

• Fix for #48 (various 0-depth issues, bad "is output start" logic)

Version 2.0.0 (breaking)

• New: automatic entity escaping for &, <, and > characters. In addition, quotes " in attributes are also escaped (see #41). Prior to this, users had to provide their own filter manually. Note that jstoxml makes an effort not to escape entities that appear to have already been encoded, to prevent double-encoding issues.
  • E.g. toXML({ foo: '1 < 2 & 2 > 1' }); // -> "1 < 2 & 2 > 1"
  • To restore the default behavior from v1.x.x, simply pass in false to filter and attributesFilter options: toXML({ foo: '1 < 2 & 2 > 1' }, { filter: false, attributesFilter: false }); // -> "1 < 2 & 2 > 1"

For more changelog history, see CHANGELOG.md.

Past changes

• See CHANGELOG.md for a full history of changes.

Other Examples

First you'll want to require jstoxml in your script, and assign the result to the namespace variable you want to use (in this case jstoxml):

// Node
const { toXML } = require('jstoxml');

// Browser (with the help of something like Webpack or Rollup)
import { toXML } from 'jstoxml';

// Browser global fallback (requires no bundler)
var toXML = window.jstoxml.toXML;

Example 1: Simple object

toXML({
    foo: 'bar',
    foo2: 'bar2'
});

Output:

barbar2

Note: because JavaScript doesn't allow duplicate key names, only the last defined key will be outputted. If you need duplicate keys, please use an array instead (see Example 2 below).

Example 2: Simple array (needed for duplicate keys)

toXML([
    {
        foo: 'bar'
    },
    {
        foo: 'bar2'
    }
]);

Output:

barbar2

Example 3: Simple functions

toXML({ currentTime: () => new Date() });

Output:

Mon Oct 02 2017 09:34:54 GMT-0700 (PDT)

Example 4: XML tag attributes

toXML({
    _name: 'foo',
    _content: 'bar',
    _attrs: {
        a: 'b',
        c: 'd'
    }
});

Output:

bar

Example 5: Tags mixed with text content

To output text content, set a key to null:

toXML({
    text1: null,
    foo: 'bar',
    text2: null
});

Output:

text1bartext2

Example 6: Nested tags (with indenting)

const xmlOptions = {
    header: false,
    indent: '  '
};

toXML(
    {
        a: {
            foo: 'bar',
            foo2: 'bar2'
        }
    },
    xmlOptions
);

Output:

<a>
  bar
  bar2
</a>

Example 7: Nested tags with attributes (with indenting)

const xmlOptions = {
    header: false,
    indent: '  '
};

toXML(
    {
        ooo: {
            _name: 'foo',
            _attrs: {
                a: 'b'
            },
            _content: {
                _name: 'bar',
                _attrs: {
                    c: 'd'
                }
            }
        }
    },
    xmlOptions
);

Output:

Note that cases like this might be especially hard to read because of the deep nesting, so it's recommend you use something like this pattern instead, which breaks it up into more readable pieces:

const bar = {
    _name: 'bar',
    _attrs: {
        c: 'd'
    }
};

const foo = {
    _name: 'foo',
    _attrs: {
        a: 'b'
    },
    _content: bar
};

const xmlOptions = {
    header: false,
    indent: '  '
};

return toXML(
    {
        ooo: foo
    },
    xmlOptions
);

Example 8: Complex functions

Function outputs will be processed (fed back into toXML), meaning that you can output objects that will in turn be converted to XML.

toXML({
    someNestedXML: () => {
        return {
            foo: 'bar'
        };
    }
});

Output:

bar

Example 9: RSS Feed

const xmlOptions = {
    header: true,
    indent: '  '
};

toXML(
    {
        _name: 'rss',
        _attrs: {
            version: '2.0'
        },
        _content: {
            channel: [
                {
                    title: 'RSS Example'
                },
                {
                    description: 'Description'
                },
                {
                    link: 'google.com'
                },
                {
                    lastBuildDate: () => new Date()
                },
                {
                    pubDate: () => new Date()
                },
                {
                    language: 'en'
                },
                {
                    item: {
                        title: 'Item title',
                        link: 'Item link',
                        description: 'Item Description',
                        pubDate: () => new Date()
                    }
                },
                {
                    item: {
                        title: 'Item2 title',
                        link: 'Item2 link',
                        description: 'Item2 Description',
                        pubDate: () => new Date()
                    }
                }
            ]
        }
    },
    xmlOptions
);

Output:

  
    <title>RSS Example</title>
    Description
    google.com
    Sat Jul 30 2011 18:14:25 GMT+0900 (JST)
    Sat Jul 30 2011 18:14:25 GMT+0900 (JST)
    en
    
      <title>Item title</title>
      Item link
      Item Description
      Sat Jul 30 2011 18:33:47 GMT+0900 (JST)
    
    
      <title>Item2 title</title>
      Item2 link
      Item2 Description
      Sat Jul 30 2011 18:33:47 GMT+0900 (JST)
    
  

Example 10: Podcast RSS Feed

(see the Apple docs for more information)

const xmlOptions = {
    header: true,
    indent: '  '
};

toXML(
    {
        _name: 'rss',
        _attrs: {
            'xmlns:itunes': 'https://www.itunes.com/dtds/podcast-1.0.dtd',
            version: '2.0'
        },
        _content: {
            channel: [
                {
                    title: 'Title'
                },
                {
                    link: 'google.com'
                },
                {
                    language: 'en-us'
                },
                {
                    copyright: 'Copyright 2011'
                },
                {
                    'itunes:subtitle': 'Subtitle'
                },
                {
                    'itunes:author': 'Author'
                },
                {
                    'itunes:summary': 'Summary'
                },
                {
                    description: 'Description'
                },
                {
                    'itunes:owner': {
                        'itunes:name': 'Name',
                        'itunes:email': 'Email'
                    }
                },
                {
                    _name: 'itunes:image',
                    _attrs: {
                        href: 'image.jpg'
                    }
                },
                {
                    _name: 'itunes:category',
                    _attrs: {
                        text: 'Technology'
                    },
                    _content: {
                        _name: 'itunes:category',
                        _attrs: {
                            text: 'Gadgets'
                        }
                    }
                },
                {
                    _name: 'itunes:category',
                    _attrs: {
                        text: 'TV & Film'
                    }
                },
                {
                    item: [
                        {
                            title: 'Podcast Title'
                        },
                        {
                            'itunes:author': 'Author'
                        },
                        {
                            'itunes:subtitle': 'Subtitle'
                        },
                        {
                            'itunes:summary': 'Summary'
                        },
                        {
                            'itunes:image': 'image.jpg'
                        },
                        {
                            _name: 'enclosure',
                            _attrs: {
                                url: 'https://example.com/podcast.m4a',
                                length: '8727310',
                                type: 'audio/x-m4a'
                            }
                        },
                        {
                            guid: 'https://example.com/archive/aae20050615.m4a'
                        },
                        {
                            pubDate: 'Wed, 15 Jun 2011 19:00:00 GMT'
                        },
                        {
                            'itunes:duration': '7:04'
                        },
                        {
                            'itunes:keywords': 'salt, pepper, shaker, exciting'
                        }
                    ]
                },
                {
                    item: [
                        {
                            title: 'Podcast2 Title'
                        },
                        {
                            'itunes:author': 'Author2'
                        },
                        {
                            'itunes:subtitle': 'Subtitle2'
                        },
                        {
                            'itunes:summary': 'Summary2'
                        },
                        {
                            'itunes:image': 'image2.jpg'
                        },
                        {
                            _name: 'enclosure',
                            _attrs: {
                                url: 'https://example.com/podcast2.m4a',
                                length: '655555',
                                type: 'audio/x-m4a'
                            }
                        },
                        {
                            guid: 'https://example.com/archive/aae2.m4a'
                        },
                        {
                            pubDate: 'Wed, 15 Jul 2011 19:00:00 GMT'
                        },
                        {
                            'itunes:duration': '11:20'
                        },
                        {
                            'itunes:keywords': 'foo, bar'
                        }
                    ]
                }
            ]
        }
    },
    xmlOptions
);

Output:

  
    <title>Title</title>
    google.com
    en-us
    Copyright 2011
    Subtitle
    Author
    Summary
    Description
    
      Name
      Email
    
    
    
      
    
    
    
      <title>Podcast Title</title>
      Author
      Subtitle
      Summary
      image.jpg
      
      https://example.com/archive/aae20050615.m4a
      Wed, 15 Jun 2011 19:00:00 GMT
      7:04
      salt, pepper, shaker, exciting
    
    
      <title>Podcast2 Title</title>
      Author2
      Subtitle2
      Summary2
      image2.jpg
      
      https://example.com/archive/aae2.m4a
      Wed, 15 Jul 2011 19:00:00 GMT
      11:20
      foo, bar
    
  

Example 11: Custom filter for XML entities, or whatever

const xmlOptions = {
    contentReplacements: {
        '<': '<',
        '>': '>',
        '"': '"',
        "'": ''',
        '&': '&'
    }
};

toXML(
    {
        foo: '<a>',
        bar: '"b"',
        baz: "'&amp;whee'"
    },
    xmlOptions
);

Output:

<a>"b"'&whee'

Example 11b: Custom filter for XML attributes

const xmlOptions = {
    attributeReplacements: {
        '<': '<',
        '>': '>',
        '"': '"',
        "'": ''',
        '&': '&'
    }
};

toXML(
    {
        _name: 'foo',
        _attrs: { a: '<"\'&"foo>' }
    },
    xmlOptions
);

Output:

Example 12: Avoiding self-closing tags

If you don't want self-closing tags, you can pass in a special config option selfCloseTags:

const xmlOptions = {
    selfCloseTags: false
};

toXML(
    {
        foo: '',
        bar: undefined
    },
    xmlOptions
);

Output:

whee

Example 13: Custom XML header

const xmlOptions = {
    header: ''
};

toXML(
    {
        foo: 'bar'
    },
    xmlOptions
);

Output:

barbar2

Example 14: Emoji attribute support (needed for AMP)

toXML({
    html: {
        _attrs: {
            '⚡': true
        }
    }
});

Output:

Example 15: Duplicate attribute key support

toXML({
    html: {
        _attrs: [
            {
                lang: 'en'
            },
            {
                lang: 'klingon'
            }
        ]
    }
});

Output:

Example 16: XML comments

toXML(
    {
        _comment: 'Some important comment',
        a: {
            b: [1, 2, 3]
        }
    },
    { indent: '    ' }
);

Output:

</a><a>
    <b>1</b>
    <b>2</b>
    <b>3</b>
</a>

Example 17: Multiple XML comments

toXML(
    [
        { _comment: 'Some important comment' },
        { _comment: 'This is a very long comment!' },
        { _comment: 'More important exposition!' },
        { a: { b: [1, 2, 3] } }
    ],
    { indent: '    ' }
);

Output:

<a>
    <b>1</b>
    <b>2</b>
    <b>3</b>
</a>

License

MIT