Triggering Error Messages

replied on June 17, 2019 • Show version history

JQuery .on method is a bit odd. If you just give the field within your table a class name and you state

$('.myFieldClass input').on('change', function)

It will look for only existing fields with that class and only monitor for changes to those, any new ones added later will be ignored.

However if you ALSO give the table a class name you can say

$('.myTableClass').on('change','.myFieldCLass input', function)

And it will always run your function regardless of when the field is added to the form

I am guessing this is because the .on is now running on something that already existed and never changes, and the field definition has been moved inside of the method itself.

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replied on June 17, 2019 • Show version history

To provide some background on this, you're right about it having to do with whether or not something exists when .on() is called.

JQuery .on() is attaching an event and it won't run again unless you call the function again.

Example 1 attaches handlers to the inputs that exist at that time.

Example 2 attaches handlers to the table, with added event delegation to target specific changes to it's child elements.

The second one works because the handler is already monitoring the parent; the "target" is part of the event so it can be identified on execution instead of just on binding.

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