Element: outerHTML property
  The outerHTML attribute of the Element
  DOM interface gets the serialized HTML fragment describing the element including its
  descendants. It can also be set to replace the element with nodes parsed from the given
  string.
  To only obtain the HTML representation of the contents of an element, or to replace the
  contents of an element, use the innerHTML property
  instead.
Value
  Reading the value of outerHTML returns a string
  containing an HTML serialization of the element and its descendants.
  Setting the value of outerHTML replaces the element and all of its
  descendants with a new DOM tree constructed by parsing the specified
  htmlString.
When set to the null value, that null value is converted to the empty string (""), so elt.outerHTML = null is equivalent to elt.outerHTML = "".
Exceptions
- SyntaxError- DOMException
- 
    Thrown if an attempt was made to set outerHTMLusing an HTML string which is not valid.
- NoModificationAllowedError- DOMException
- 
    Thrown if an attempt was made to set outerHTMLon an element which is a direct child of aDocument, such asDocument.documentElement.
Examples
Getting the value of an element's outerHTML property
HTML
<div id="d">
  <p>Content</p>
  <p>Further Elaborated</p>
</div>
JavaScript
const d = document.getElementById("d");
console.log(d.outerHTML);
// The string '<div id="d"><p>Content</p><p>Further Elaborated</p></div>'
// is written to the console window
Replacing a node by setting the outerHTML property
HTML
<div id="container">
  <div id="d">This is a div.</div>
</div>
JavaScript
const container = document.getElementById("container");
const d = document.getElementById("d");
console.log(container.firstElementChild.nodeName); // logs "DIV"
d.outerHTML = "<p>This paragraph replaced the original div.</p>";
console.log(container.firstElementChild.nodeName); // logs "P"
// The #d div is no longer part of the document tree,
// the new paragraph replaced it.
Notes
  If the element has no parent node, setting its outerHTML property will not change it
  or its descendants. For example:
const div = document.createElement("div");
div.outerHTML = '<div class="test">test</div>';
console.log(div.outerHTML); // output: "<div></div>"
  Also, while the element will be replaced in the document, the variable whose
  outerHTML property was set will still hold a reference to the original
  element:
const p = document.querySelector("p");
console.log(p.nodeName); // shows: "P"
p.outerHTML = "<div>This div replaced a paragraph.</div>";
console.log(p.nodeName); // still "P";
The returned value will contain HTML escaped attributes:
const anc = document.createElement("a");
anc.href = "https://developer.mozilla.org?a=b&c=d";
console.log(anc.outerHTML); // output: "<a href='https://developer.mozilla.org?a=b&c=d'></a>"
Specifications
| Specification | 
|---|
| HTML Standard # dom-element-outerhtml | 
Browser compatibility
BCD tables only load in the browser
See also
- Serializing DOM trees into XML strings: XMLSerializer
- Parsing XML or HTML into DOM trees: DOMParser
- HTMLElement.outerText