xml2ts

This is a remixed version of the original work of Marek Kubica's node-xml2js.

####Differences between this and the original version

• Complete rewrite in typescript.
• Some features removed because of the increased strictness of being type safe.
• Some features or behaviours altered.
• Introduced XmlTsNode as resulting object.
• Typed configuration object
• Typed validators and processors
• Position tracking. You always know the actual node position within the original xml.
• Tests are rewrote to a more standard Mocha and Chai.

Documentation and the builder side is still in progress. The parsing side is done

Description

Simple XML to JavaScript object converter. Uses sax-js and xmlbuilder-js.

Note: If you're looking for a full DOM parser, you probably want JSDom.

This version is somewhat rewrote to typescript. Introduced XmlTsNode as the resulting object. Position of each node are

Ever had the urge to parse XML? And wanted to access the data in some sane, easy way? Don't want to compile a C parser, for whatever reason? Then xml2js is what you're looking for!

Installation

Simplest way to install xml2ts is to use npm, just npm install xml2ts which will download xml2js and all dependencies.

Usage

No extensive tutorials required because you are a smart developer! The task of parsing XML should be an easy one, so let's make it so! Here's some examples.

Shoot-and-forget usage

You want to parse XML as simple and easy as possible? It's dangerous to go alone, take this:

import {parseString} from 'xml2ts';
var xml = "<root>Hello xml2js!</root>"
const result = await parseString(xml);

If you need some special options, fear not, xml2ts supports a number of options (see below), you can specify these as second argument:

import {parseString} from 'xml2ts';
parseString(xml, {trim: true});

Simple as pie usage

That's right, if you have been using xml-simple or a home-grown wrapper, this was added in 0.1.11 just for you:

import * as fs = from 'fs';
import {Parser, parserDefaults, XmlTsNode} from 'xml2ts';

async function f(xml: string): Promise<XmlTsNode> {
  const parser = new Parser(parserDefaults);
  return await parser.parseString(xml);
}

Parsing multiple files

If you want to parse multiple files, you have multiple possibilities:

• You can create one xml2js.Parser per file. That's the recommended one and is promised to always just work.

So you wanna some JSON?

Just wrap the result object in a call to JSON.stringify like this JSON.stringify(result). You get a string containing the JSON representation of the parsed object that you can feed to JSON-hungry consumers.

Adding xmlns attributes

You can generate XML that declares XML namespace prefix / URI pairs with xmlns attributes.

Example declaring a default namespace on the root element:

let obj = { 
  Foo: {
    $: {
      "xmlns": "http://foo.com"
    }   
  }
};  

Result of buildObject(obj):

<Foo xmlns="http://foo.com"/>

Example declaring non-default namespaces on non-root elements:

let obj = {
  'foo:Foo': {
    $: {
      'xmlns:foo': 'http://foo.com'
    },
    'bar:Bar': {
      $: {
        'xmlns:bar': 'http://bar.com'
      }
    }
  }
}

Result of buildObject(obj):

<foo:Foo xmlns:foo="http://foo.com">
  <bar:Bar xmlns:bar="http://bar.com"/>
</foo:Foo>

Processing attribute, tag names and values

Since 0.4.1 you can optionally provide the parser with attribute name and tag name processors as well as element value processors (Since 0.4.14, you can also optionally provide the parser with attribute value processors):

function nameToUpperCase(name){
    return name.toUpperCase();
}

//transform all attribute and tag names and values to uppercase
parseString(xml, {
  tagNameProcessors: [nameToUpperCase],
  attrNameProcessors: [nameToUpperCase],
  valueProcessors: [nameToUpperCase],
  attrValueProcessors: [nameToUpperCase]},
  function (err, result) {
    // processed data
});

The tagNameProcessors and attrNameProcessors options accept an Array of functions with the following signature:

function (name){
  //do something with `name`
  return name
}

The attrValueProcessors and valueProcessors options accept an Array of functions with the following signature:

function (value, name) {
  //`name` will be the node name or attribute name
  //do something with `value`, (optionally) dependent on the node/attr name
  return value
}

Some processors are provided out-of-the-box and can be found in lib/processors.js:

• normalize: transforms the name to lowercase. (Automatically used when options.normalize is set to true)

• firstCharLowerCase: transforms the first character to lower case. E.g. 'MyTagName' becomes 'myTagName'

• stripPrefix: strips the xml namespace prefix. E.g <foo:Bar/> will become 'Bar'. (N.B.: the xmlns prefix is NOT stripped.)

• parseNumbers: parses integer-like strings as integers and float-like strings as floats E.g. "0" becomes 0 and "15.56" becomes 15.56

• parseBooleans: parses boolean-like strings to booleans E.g. "true" becomes true and "False" becomes false

Options

Apart from the default settings, there are a number of options that can be specified for the parser. Options are specified by new Parser({optionName: value}). Possible options are:

• attrkey (default: $): Prefix that is used to access the attributes. Version 0.1 default was @.
• charkey (default: _): Prefix that is used to access the character content. Version 0.1 default was #.
• explicitCharkey (default: false)
• trim (default: false): Trim the whitespace at the beginning and end of text nodes.
• normalizeTags (default: false): Normalize all tag names to lowercase.
• normalize (default: false): Trim whitespaces inside text nodes.
• explicitRoot (default: true): Set this if you want to get the root node in the resulting object.
• emptyTag (default: ''): what will the value of empty nodes be.
• explicitArray (default: true): Always put child nodes in an array if true; otherwise an array is created only if there is more than one.
• ignoreAttrs (default: false): Ignore all XML attributes and only create text nodes.
• mergeAttrs (default: false): Merge attributes and child elements as properties of the parent, instead of keying attributes off a child attribute object. This option is ignored if ignoreAttrs is true.
• validator (default null): You can specify a callable that validates the resulting structure somehow, however you want. See unit tests for an example.
• xmlns (default false): Give each element a field usually called '$ns' (the first character is the same as attrkey) that contains its local name and namespace URI.
• explicitChildren (default false): Put child elements to separate property. Doesn't work with mergeAttrs = true. If element has no children then "children" won't be created. Added in 0.2.5.
• childkey (default $$): Prefix that is used to access child elements if explicitChildren is set to true. Added in 0.2.5.
• preserveChildrenOrder (default false): Modifies the behavior of explicitChildren so that the value of the "children" property becomes an ordered array. When this is true, every node will also get a #name field whose value will correspond to the XML nodeName, so that you may iterate the "children" array and still be able to determine node names. The named (and potentially unordered) properties are also retained in this configuration at the same level as the ordered "children" array. Added in 0.4.9.
• charsAsChildren (default false): Determines whether chars should be considered children if explicitChildren is on. Added in 0.2.5.
• includeWhiteChars (default false): Determines whether whitespace-only text nodes should be included. Added in 0.4.17.
• async (default false): Should the callbacks be async? This might be an incompatible change if your code depends on sync execution of callbacks. Future versions of xml2js might change this default, so the recommendation is to not depend on sync execution anyway. Added in 0.2.6.
• strict (default true): Set sax-js to strict or non-strict parsing mode. Defaults to true which is highly recommended, since parsing HTML which is not well-formed XML might yield just about anything. Added in 0.2.7.
• attrNameProcessors (default: null): Allows the addition of attribute name processing functions. Accepts an Array of functions with following signature:

  function (name){
      //do something with `name`
      return name
  }

  Added in 0.4.14
• attrValueProcessors (default: null): Allows the addition of attribute value processing functions. Accepts an Array of functions with following signature:

  function (name){
    //do something with `name`
    return name
  }

  Added in 0.4.1
• tagNameProcessors (default: null): Allows the addition of tag name processing functions. Accepts an Array of functions with following signature:

  function (name){
    //do something with `name`
    return name
  }

  Added in 0.4.1
• valueProcessors (default: null): Allows the addition of element value processing functions. Accepts an Array of functions with following signature:

  function (name){
    //do something with `name`
    return name
  }

  Added in 0.4.6

Running tests, development

The development requirements are handled by npm, you just need to install them. We also have a number of unit tests, they can be run using npm test directly from the project root. This runs zap to discover all the tests and execute them.

If you like to contribute, keep in mind that xml2ts is written in Typescript, so don't develop on the JavaScript files that are checked into the repository for convenience reasons. Also, please write some unit test to check your behaviour and if it is some user-facing thing, add some documentation to this README, so people will know it exists. Thanks in advance!

Getting support

Please, if you have a problem with the library, first make sure you read this README. If you read this far, thanks, you're good. Then, please make sure your problem really is with xml2ts. It is? Okay, then I'll look at it. Send me a mail and we can talk. Please don't open issues, as I don't think that is the proper forum for support problems. Some problems might as well really be bugs in xml2ts, if so I'll let you know to open an issue instead :)

But if you know you really found a bug, feel free to open an issue instead.