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async attribute | async property

Provides control of when a script executes while a document loads. Setting a script to run asynchronously can improve performance by unblocking the rest of the document. When async = false, it can preserve execution order to ensure dependent scripts are run in order.

This property is read/write.

Internet Explorer 10



<element async="ptr" ... >


object.async = ptr
ptr = object.async


Property values

Type: boolean

When true, the script will execute asynchronously, otherwise script is executed as page loads.


Starting with Windows 8.1, dynamically added script elements load asynchronously for Windows Runtime apps using JavaScript. To learn more, see API Changes for Windows 8.1.

See also




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