In JavaScript, how do you determine the current event if not passed as arg? - Stack Overflow

In an arbitrary JavaScript function, I wish to determine the upstream event.

The event listener function did not pass the event do the current function. As far as I know, window.event is not WC3 and not available.

function listener(e) { subfunc(e.target); }

function subfunc( element) {
    // here I wish to know which if any event responsible for me being called
    var event = ?;
    switch( event.type ) { ... }
}

How does function subfunc() determine the current event?

(Apologize if question asked before - seems it must have been - but cannot track it down.)

In an arbitrary JavaScript function, I wish to determine the upstream event.

The event listener function did not pass the event do the current function. As far as I know, window.event is not WC3 and not available.

function listener(e) { subfunc(e.target); }

function subfunc( element) {
    // here I wish to know which if any event responsible for me being called
    var event = ?;
    switch( event.type ) { ... }
}

How does function subfunc() determine the current event?

(Apologize if question asked before - seems it must have been - but cannot track it down.)

• javascript
• dom-events

Share Improve this question Follow edited Jan 15, 2023 at 14:13 Brian Tompsett - 汤莱恩 5,8937272 gold badges6161 silver badges133133 bronze badges asked Sep 23, 2011 at 9:33 cc youngcc young 20.3k3232 gold badges9595 silver badges150150 bronze badges 5

• 2 Your only chance is to pass e to subfunc, not only e.target. Or you set window.event = e; inside listener, but passing the event object seems to be a cleaner approach to me. – Felix Kling Commented Sep 23, 2011 at 9:36
• @Felix - on setting window.event, seems dangerous to try to maintain that state space. – cc young Commented Sep 23, 2011 at 9:42
• @spender - wow! seems like that would be a pretty useful thing to know. – cc young Commented Sep 23, 2011 at 9:42
• @ccyoung: Agreed, that's why I said passing the event object is better :) – Felix Kling Commented Sep 23, 2011 at 9:43
• @Felix - right! seems a choice between extra arg and this. playing with code psychology now. – cc young Commented Sep 23, 2011 at 9:54

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2 Answers 2

Sorted by: Reset to default 3

You can do:

function listener(e) { subfunc.call(this, e); }

function subfunc( e ) {
    var element = this; //<- 'this' points to your element, 'e.type' is event type
    switch( e.type ) { ... }
}

Also other way:

function listener(e) { subfunc.call(e, e.target); }

function subfunc( element ) {
    var event = this; //<- 'this' points to your event object
    switch( event.type ) { ... }
}

That's not possible. There's only one property which can be accessed through another, reliable way: event.target = this (Provided that the function is called from within the scope of the event listener).

The event object should be passed to subfunc.