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element.innerHTML

The Element.innerHTML property sets or gets the HTML syntax describing the element's descendants.

Note: If a <div>, <span>, or <noembed> node has a child text node that includes the characters (&), (<), or (>), innerHTML returns these characters as &amp, &lt and &gt respectively. Use Node.textContent to get a correct copy of these text nodes' contents.

Syntax

const content = element.innerHTML;

On return, content contains the serialized HTML code describing all of the element's descendants.

 element.innerHTML = content;

Removes all of element's children, parses the content string and assigns the resulting nodes as children of the element.

Example

<html>
  <head></head>
  <body>
    <div id="txt">
      <script     id="txt0"> x=0> </script>
        <noembed    id="txt1"> 1   </noembed>
        <noframes   id="txt2"> 2   </noframes>
        <noscript   id="txt3"> 3   </noscript>
        <div        id="txt4"> 4   </div>
        <div>
          <noscript id="txt5"> 5   </noscript>
        </div>
        <span       id="txt6"> 6   </span>
      </div>

      <div id="innerHTMLtxt"></div>
    <div id="textContenttxt"><div>

    <script> 
    for (let i = 0; i < 7; i++) { 
      x = "txt" + i;
      document.getElementById(x).firstChild.nodeValue = '&<>'
    }

    document.getElementById("innerHTMLtxt").textContent =
        document.getElementById("txt").innerHTML
    document.getElementById("textContenttxt").textContent =
        document.getElementById("txt").textContent
    </script>
  <body>
</html>

// HTML:
// <div id="d"><p>Content</p>
// <p>Further Elaborated</p>
// </div>

const d = document.getElementById("d");
dump(d.innerHTML);

// the string "<p>Content</p><p>Further Elaborated</p>"
// is dumped to the console window

Notes

This property provides a simple way to completely replace the contents of an element. For example, the entire contents of the document body can be deleted by:

document.body.innerHTML = "";  // Replaces body content with an empty string.

The innerHTML property of many types of elements—including <body> or <html>—can be returned or replaced. It can also be used to view the source of a page that has been modified dynamically:

// Copy and paste into address bar as a single line
javascript:"<pre>"+document.documentElement.innerHTML.replace(/</g,"&lt;") + "</pre>";

This property was initially implemented by web browsers, then specified by the WHATWG and W3C in HTML5. Old implementations may not all implement it exactly the same way. For example, when text is entered into a text input, Internet Explorer changes the value attribute of the input's innerHTML property but Gecko browsers do not.

Security considerations

It is not uncommon to see innerHTML used to insert text in a web page. This comes with a security risk.

const name = "John";
// assuming 'el' is an HTML DOM element
el.innerHTML = name; // harmless in this case

// ...

name = "<script>alert('I am John in an annoying alert!')</script>";
el.innerHTML = name; // harmless in this case

Although this may look like a cross-site scripting attack, the result is harmless. HTML5 specifies that a <script> tag inserted via innerHTML should not execute.

However, there are ways to execute JavaScript without using <script> elements, so there is still a security risk whenever you use innerHTML to set strings over which you have no control. For example:

const name = "<img src='x' onerror='alert(1)'>";
el.innerHTML = name; // shows the alert

For that reason, it is recommended you not use innerHTML when inserting plain text; instead, use node.textContent. This doesn't interpret the passed content as HTML, but instead inserts it as raw text.

Specification