This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.


Fired when the code in a <script> element declared in an HTML document is about to start executing. Does not fire if the element is added dynamically, eg with appendChild().


document.onbeforescriptexecute = funcRef;

funcRef is a function reference, called when the event is fired. The event's target attribute is set to the script Element that is about to be executed.


function starting(e) {
  logMessage("Starting script with ID: " +;

document.addEventListener("beforescriptexecute", starting, true);

View Live Examples


See also

Document Tags and Contributors

 Last updated by: teoli,