xml2js-parser

Simple XML to JavaScript object converter that uses a sax-js for parsing. Support async as native promise or callback and sync mode operation.

Description

This is a fork from a wonderful xml2js module.

It aims to keep backwards compatibility with xml2js version 0.4.17 and target nodejs v6.x but without XML building support.

Motivation behind fork was:

• do not use coffee-script
• do one thing and do it well (no builder)
• minimal dependency tree (no lodash)
• use javascript new features from node v6.x

Installation

Yo install just type npm install xml2js-parser which will download xml2js-parser and dependencies.

Shoot-and-forget usage

You want to parse XML as simple and easy as possible? Take this:

const parseString = require('xml2js-parser').parseString;
const xml = '<root>Hello xml2js-parser!</root>';
parseString(xml, (err, result) => {
  console.log(result);
});

If you need some special options, xml2js-parser supports a number of options (see below), you can specify these as second argument:

parseString(xml, {trim: true}, function (err, result) => {
  // processed data
});

New promises usage

const parseString = require('xml2js-parser').parseString;
 
const xml = '<root>Hello xml2js-parser!</root>';
parseString(xml)
.then(res) => console.log(res))
.catch(err) => console.error(err));

Standard usage

const fs = require('fs');
const Parser = require('xml2js-parser');
 
var parser = new Parser({trim: true});
fs.readFile(__dirname + '/foo.xml', (err, xml) => {
  parser.parseString(xml, (err, result) => {
    console.dir(result);
  });
});

Sync mode

const fs = require('fs');
const parseStringSync = require('xml2js-parser').parseStringSync;
 
fs.readFile(__dirname + '/foo.xml', (err, xml) => {
  try {
    const res = parseStringSync(xml);
    console.log(res);
  } catch (err)  {
    console.error(err);
  }
});

Processing attribute, tag names and values

You can optionally provide the parser with attribute name and tag name processors as well as element 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]},
  (err, result) => {
    // processed data
});

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

function (name) { //do something with name and return result }

Some processors are provided out-of-the-box and can be found in code:

• normalize: transforms the name to lowercase. (Automatically used when normalize option 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: $): Prefix that is used to access the attributes.
• charkey (default: _): Prefix that is used to access the character content.
• explicitCharkey (default: false)
• trim (default: false): Trim the whitespace at the beginning and end of text nodes.
• normalizeTags (default: false): Normalize all tag names to lowercase.
• normalize (default: false): Trim whitespaces inside text nodes.
• explicitRoot (default: true): Set this if you want to get the root node in the resulting object.
• emptyTag (default: ''): what will the value of empty nodes be.
• explicitArray (default: true): Always put child nodes in an array if true; otherwise an array is created only if there is more than one.
• ignoreAttrs (default: false): Ignore all XML attributes and only create text nodes.
• mergeAttrs (default: false): Merge attributes and child elements as properties of the parent, instead of keying attributes off a child attribute object. This option is ignored if ignoreAttrs is false.
• validator (default null): You can specify a callable that validates the resulting structure somehow, however you want. See unit tests for an example.
• xmlns (default false): Give each element a field usually called '$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.
• childkey (default $$): Prefix that is used to access child elements if explicitChildren is set to true.
• 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.
• charsAsChildren (default false): Determines whether chars should be considered children if explicitChildren is on.
• includeWhiteChars (default false): Determines whether whitespace-only text nodes should be included.
• 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.
• attrNameProcessors (default: null): Allows the addition of attribute name processing functions. Accepts an Array of functions.
• attrValueProcessors (default: null): Allows the addition of attribute value processing functions. Accepts an Array of functions.
• tagNameProcessors (default: null): Allows the addition of tag name processing functions. Accepts an Array of functions.
• valueProcessors (default: null): Allows the addition of element value processing functions. Accepts an Array of functions.

Getting support

If you know you really found a bug, feel free to open an issue.

Running tests, development

The development requirements are handled by npm install if you clone repository. 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.

How to contribute

I'm always happy about useful new pull requests. Keep in mind that the better your pull request is, the easier it can be added to xml2js-parser. As such please make sure your patch is ok:

• xml2js-parser is written in ECMAScript 2015 for node v6.x, respect it.
• Make sure that the unit tests still all pass.
• Please, add a unit test with your pull request, to show what was broken and is now fixed or what was impossible and now works due to your new code.
• If you add a new feature, please add some documentation that it exists.

If you like, you can add yourself in the package.json as contributor if you deem your contribution significant enough.