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Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.
Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
The beforescriptexecute event fires when a static <script> is about to start executing. It does not fire if the element is added dynamically, such as with appendChild().
Use the event name in methods like addEventListener(), or set an event handler property.
A generic Event.
Not part of any specification.
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This page was last modified on Sep 25, 2025 by MDN contributors.
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