Convert XML to JSON (and back) using Javascript

Question

How would you convert from XML to JSON and then back to XML?

The following tools work quite well, but aren\'t completely consistent:

• xml2json

Answer 1

I was using xmlToJson just to get a single value of the xml.
I found doing the following is much easier (if the xml only occurs once..)

let xml =
'<person>' +
  ' <id>762384324</id>' +
  ' <firstname>Hank</firstname> ' +
  ' <lastname>Stone</lastname>' +
'</person>';

let getXmlValue = function(str, key) {
  return str.substring(
    str.lastIndexOf('<' + key + '>') + ('<' + key + '>').length,
    str.lastIndexOf('</' + key + '>')
  );
}


alert(getXmlValue(xml, 'firstname')); // gives back Hank

Answer 2

A while back I wrote this tool https://bitbucket.org/surenrao/xml2json for my TV Watchlist app, hope this helps too.

Synopsys: A library to not only convert xml to json, but is also easy to debug (without circular errors) and recreate json back to xml. Features :- Parse xml to json object. Print json object back to xml. Can be used to save xml in IndexedDB as X2J objects. Print json object.

Answer 3

I think this is the best one: Converting between XML and JSON

Be sure to read the accompanying article on the xml.com O'Reilly site, which goes into details of the problems with these conversions, which I think you will find enlightening. The fact that O'Reilly is hosting the article should indicate that Stefan's solution has merit.

Answer 4

I've created a recursive function based on regex, in case you don't want to install library and understand the logic behind what's happening:

const xmlSample = '<tag>tag content</tag><tag2>another content</tag2><tag3><insideTag>inside content</insideTag><emptyTag /></tag3>';
console.log(parseXmlToJson(xmlSample));

function parseXmlToJson(xml) {
    const json = {};
    for (const res of xml.matchAll(/(?:<(\w*)(?:\s[^>]*)*>)((?:(?!<\1).)*)(?:<\/\1>)|<(\w*)(?:\s*)*\/>/gm)) {
        const key = res[1] || res[3];
        const value = res[2] && parseXmlToJson(res[2]);
        json[key] = ((value && Object.keys(value).length) ? value : res[2]) || null;

    }
    return json;
}

Regex explanation for each loop:

• res[0] - return the xml (as is)
• res[1] - return the xml tag name
• res[2] - return the xml content
• res[3] - return the xml tag name in case the tag closes itself. In example: <tag />

You can check how the regex works here: https://regex101.com/r/ZJpCAL/1

Note: In case json has a key with an undefined value, it is being removed. That's why I've inserted null at the end of line 9.

Answer 5

In 6 simple ES6 lines:

xml2json = xml => {                                                                                                                                                     
  var el = xml.nodeType === 9 ? xml.documentElement : xml                                                                                                               
  var h  = {name: el.nodeName}                                                                                                                                          
  h.content    = Array.from(el.childNodes || []).filter(e => e.nodeType === 3).map(e => e.textContent).join('').trim()                                                  
  h.attributes = Array.from(el.attributes || []).filter(a => a).reduce((h, a) => { h[a.name] = a.value; return h }, {})                                                 
  h.children   = Array.from(el.childNodes || []).filter(e => e.nodeType === 1).map(c => h[c.nodeName] = xml2json(c))                                                    
  return h                                                                                                                                                              
}  

Test with echo "xml2json_example()" | node -r xml2json.es6 with source at https://github.com/brauliobo/biochemical-db/blob/master/lib/xml2json.es6

Answer 6

Here' a good tool from a documented and very famous npm library that does the xml <-> js conversions very well: differently from some (maybe all) of the above proposed solutions, it converts xml comments also.

var obj = {name: "Super", Surname: "Man", age: 23};

var builder = new xml2js.Builder();
var xml = builder.buildObject(obj);