This deprecated, poor-supported element is not recommended. Authors should generally find an alternative way to accomplish the same task while adhering to all best practices, or simply do without it if it is unimportant.
The void HTML
<isindex /> element has been deprecated since HTML4 for its poorly supported method for providing a searchable index related to the current document. Originally, it was intended (by the W3C) that this element should be placed inside the
<head> of the document, but most browsers allowed it to be used anywhere in the document. This element has been deprecated in favor of
<input type="search" />.
|URL||Identifies the URL of the script that will process the search.|
|URL|| Older implementation that was used before |
|text||Provides prompt text that appears next to search input.|
- Global Attributes
<isindex prompt="Tell me:" />