btw: With addEventListener, we have to use hard coded strings for the
event name. Eg:
img.addEventListener("load", e -> doStuff());
Or are there event name constants we can use somewhere?
On Thursday, 31 July 2025 at 7:29:07 pm UTC+10 Craig Mitchell wrote:
> Excellent explanations. Makes sense. Thanks Jens.
>
> On Thursday, 31 July 2025 at 7:25:56 pm UTC+10 Jens wrote:
>
>> What I don't understand is why onload and onerror need a return value? I
>> just return null as I've no clue what the return value should be.
>>
>>
>> Because these on<Event> properties and their functions are defined that
>> way. For example in the old days you could return false in an onclick
>> function to suppress the click default action of the browser. These days it
>> is recommended to always use addEventListener() instead of these event
>> properties and to suppress the default action you call
>> event.preventDefault().
>>
>> Also in JS a function basically always have some return value, e.g.
>>
>> function() {
>> return;
>> return undefined;
>> // no return statement at all
>> }
>>
>> is all the same and returns undefined. That is why Promises in elemental2
>> also feel a bit clunky compared to JS. Promises allow you to return a new
>> Promise/thenable in your success/catch callback methods so elemental2 has
>> to define a return type for these callback functions. If you do not want to
>> return a Promise/thenable in JS then you simply do not write a return
>> statement but in Java you now have to write return null.
>>
>> -- J.
>>
>
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