Are event handlers in JavaScript called in order?
This has been changed with DOM3! While the DOM level 2 events specification did state
When the event reaches the target, any event listeners registered on the
EventTarget
are triggered. Although allEventListeners
on theEventTarget
are guaranteed to be triggered by any event which is received by thatEventTarget
, no specification is made as to the order in which they will receive the event with regards to the otherEventListeners
on theEventTarget
.
The current DOM level 3 events specification does now state
The implementation MUST determine the current target's candidate event listeners. This MUST be the list of all event listeners that have been registered on the current target in their order of registration.
HTML5
defines the ordering of listeners registered through event handler attributes. […]Finally, the implementation MUST process all candidate event handlers in order […]
However, I can't find a reference to this behaviour in the DOM 4 draft any more.
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Sasha Chedygov
Stuff I'm great at: Frontend JavaScript (esp. React), Python, Node.js, HTML/CSS Stuff I'm good at: SQL, UX Stuff I'm learning: Rust, cloud infrastructure stuff
Updated on September 22, 2020Comments
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Sasha Chedygov over 3 years
If I attach multiple event handlers to a single event on a single DOM element, are the event handlers guaranteed to be called in the order they were added? Or should I not rely on this behavior?
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thomasrutter almost 8 yearsPresumably if this comes from HTML5 it means that current browsers already do this, do you think?
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Bergi almost 8 years@thomasrutter: Yes, pretty much - they only standardise what they implement.
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Tomasz P. Szynalski over 4 yearsThe answer appears to be out of date. The current DOM Level 3 spec doesn't include the quoted paragraph about candidate event listeners anymore, unfortunately.