HTML <script> defer Attribute
A script that will not run until after the page has loaded:
Definition and Usage
The defer attribute is a boolean attribute.
When present, it specifies that the script is executed when the page has finished parsing.
Note: The defer attribute is only for external scripts (should only be used if the src attribute is present).
Note: There are several ways an external script can be executed:
- If async is present: The script is executed asynchronously with the rest of the page (the script will be executed while the page continues the parsing)
- If async is not present and defer is present: The script is executed when the page has finished parsing
- If neither async or defer is present: The script is fetched and executed immediately, before the browser continues parsing the page
The numbers in the table specify the first browser version that fully supports the attribute.
❮ HTML <script> tag