When is a CDATA section necessary within a script tag?

When working with JavaScript inside HTML documents, developers may come across the CDATA section. It can be helpful when dealing with older XHTML documents or embedded JavaScript in XML-based markup.

What is a CDATA Section?

A CDATA (Character Data) section is a special syntax used in XML and XHTML documents to prevent certain characters from being interpreted as markup. It ensures that special characters like < and & are treated as plain text rather than triggering parsing errors.

Syntax ?

<![CDATA[
    JavaScript code goes here...
]]>

Why Was CDATA Used <script> tag?

To avoid parsing the symbols <> &, it is added in <script>?</script>. It is not needed in HTML. Let us see how CDATA is added in <script> tags ?

<script>
   //<![CDATA[
      document.write(">");
   //]]>
</script>

Note: CDATA is now deprecated. Do not use.

When is CDATA Necessary Today?

While CDATA is unnecessary in modern HTML5, it might still be required in ?

• XHTML Documents (.xhtml) - When serving pages as application/xhtml+xml.
  
• Embedded JavaScript in XML - When JavaScript is inside an SVG or RSS feed (which follows XML rules).

Conclusion

CDATA sections were historically necessary when writing JavaScript inside XHTML or XML-based documents to prevent parsing errors. However, modern HTML5 does not require CDATA, and it is rarely used today.