In my javascript I have the following:

let person = document.createElement('person');
let name = document.createElement('name');
let surname = document.createElement('surname');
person.appendChild(name);
person.appendChild(surname);

let xml = person;

How do I save my "xml" variable in a file (using javascript only)? OBS: The content should not be presented in a single line, but in the tree structure:

<person>
    <name></name>
    <surname></surname>
</person>

In my javascript I have the following:

let person = document.createElement('person');
let name = document.createElement('name');
let surname = document.createElement('surname');
person.appendChild(name);
person.appendChild(surname);

let xml = person;

How do I save my "xml" variable in a file (using javascript only)? OBS: The content should not be presented in a single line, but in the tree structure:

<person>
    <name></name>
    <surname></surname>
</person>

• javascript
• xml
• dom

• Client-side JS or server-side (Node)? Regarding the formatting, there are some existing library functions for pretty-printing XML. – nnnnnn Commented Apr 3, 2017 at 3:09
• Would you be willing to accept an answer with JSON output instead of XML? JS has native ways of serializing to JSON but not XML – Rico Kahler Commented Apr 3, 2017 at 3:12
• I lied--there are native ways of serializing to XML using XMLSerializer. my answer uses it – Rico Kahler Commented Apr 3, 2017 at 3:48

2 Answers 2

There's a very simple way to serialize your document to XML using XMLSerializer.

Here is the process:

1. give an elment to XMLSerializer to serialize to XHTML (which is valid XML).
2. optionally remove the xhtml namespace using String.prototype.replace
3. use vkbeautify to pretty print (no native way to pretty print)

let person = document.createElement('person');
let name = document.createElement('name');
let surname = document.createElement('surname');
person.appendChild(name);
person.appendChild(surname);

// 1.) use XMLSerializer
let xml = new XMLSerializer().serializeToString(person);

// 2.) remove xml namespace
let xmlWithoutNamespace = xml.replace(' xmlns="http://www.w3/1999/xhtml"', '');

// 3.) use vkbeautify or your other favorite library to pretty print
console.log(vkbeautify.xml(xmlWithoutNamespace));

<script src="https://storage.googleapis./google-code-archive-downloads/v2/code.google./vkbeautify/vkbeautify.0.99.00.beta.js"></script>

You can use .outerHTML to get string containing person node and child nodes, data URI representation of file, set a href of <a> element with download attribute set.

let person = document.createElement('person');
let name = document.createElement('name');
let surname = document.createElement('surname');
person.appendChild(name);
person.appendChild(surname);

let xml = `data:application/xml,<?xml version="1.0" encoding="UTF-8"?>${encodeURIComponent(person.outerHTML)}`;

console.log(person, xml);

window.onload = () => {
  let a = document.createElement("a");
  let filename = "xmlfile.xml";
  a.download = a.textContent =  "xmlfile.xml";
  a.href = xml;
  document.body.appendChild(a);
}

You can alternatively create a Blob or File instance representing XML data

let person = document.createElement('person');
let name = document.createElement('name');
let surname = document.createElement('surname');
person.appendChild(name);
person.appendChild(surname);

let xml = `<?xml version="1.0" encoding="UTF-8"?>${person.outerHTML}`;

let file = new File([xml]
           , "xmlfile.xml", {type:"application/xml"});

console.log(person, xml, file);

let url;

window.onload = () => {
  let a = document.createElement("a");
  let filename = "xmlfile.xml";
  a.download = a.textContent =  "xmlfile.xml";
  url = URL.createObjectURL(file);
  a.href = url;
  document.body.appendChild(a);
  a.onclick = () => {
    window.onfocus = () => {
      window.onfocus = null;
      URL.revokeObjectURL(url);
      if ("close" in file && !file.isClosed) file.close();
    }
  }
}

See also How to download a file without using <a> element with download attribute or a server?