HTML: Custom Tag (Custom Element)

What is Custom Tag

you can define a custom element.

the name must start with lower case a to z, then followed by a hyphen, then more letters.

<abc-xyz>custom element</abc-xyz>

you can use CSS to define its appearance and use JavaScript to define its behavior.

Custom element name restrictions

1. All characters must be lowercase.
2. Start with lowercase a to z
3. Followed by zero or more simple Unicode character
4. Followed by a hyphen
5. Followed by zero or more simple Unicode character

the “simple Unicode character” includes Emoji 😄

Reference

• https://html.spec.whatwg.org/multipage/custom-elements.html#custom-elements