Syncing localStorage across instances

[bedeoverend]

Are there any plans to have this sync changes to localStorage that occur on the same page, is this already implemented? Or at least for changes made through other instances of iron-localstorage - similar to iron-meta? I have multiple instances of iron-localstorage referencing the same key, and seems - at least for me - like a common use case to want them all to update when any one of them update.

[atotic]

We've decided not to do it in order to keep the code clean, it was just a wrapper for localstorage API.

There are no current plans to extend it. I see the need, so this might change. We've created many elements with global state.

[43081j]

For anyone wondering why this is the case, iron-localstorage actually does implement this correctly. It is browser behaviour/implementation which prevents this.

See here.

When you call setItem (which iron-localstorage does), the storage event will fire only if window is a different window to the one in which setItem was called (so iron-localstorage is never notified).

[bamartin-ua]

For those looking for a work-around, any time you change value, you can call window.setTimeout(e => window.dispatchEvent(new StorageEvent('storage',{key:<<name here>>,newValue:<<value here>>}))).
this is a setTimeout so it obviously creates a race condition, but it works for the general case.
I think localstorage actually ignores the newValue but that could change in the future?

I also played around with the iron-localstorage code, and adding the appropriate dispatchEvent call in the save() function works great, but I could see some app expecting that storage events wouldn't fire on-page, given that's kindof in the spec. perhaps a better solution would be to have iron-localstorage fire and listen for a custom ls-storage event or somesuch?