What is HTML <script> async Attribute
Definition and Usage
The async attribute is a boolean attribute.
If the async attribute is set, the script is downloaded in parallel to parsing the page, and executed as soon as it is available. The parsing of the page is interrupted once the script is downloaded completely, and then the script is executed, before the parsing of the rest of the page continues.
Note: The async attribute is only for external scripts (and should only be used if the src attribute is present).
Note: There are several ways an external script can be executed:
- If
asyncis present: The script is downloaded in parallel to parsing the page, and executed as soon as it is available (before parsing completes) - If
deferis present (and notasync): The script is downloaded in parallel to parsing the page, and executed after the page has finished parsing - If neither
asyncordeferis present: The script is downloaded and executed immediately, blocking parsing until the script is completed
Browser Support
The numbers in the table specify the first browser version that fully supports the attribute.
Syntax
<script async>
Category: | Web Tutorial |
Sub Category: | HTML Tag |
Uploaded by: | Admin |