Initial implementation of hot elements. #1
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| (maybe: Constructor<HTMLElement>): maybe is HotReloadableElementClass => { | ||
| // This isn't safe against name mangling, but this is definitely debug | ||
| // code, so that's fine. | ||
| return 'notifyOnHotModuleReload' in maybe; |
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how about using typeof maybe.notifyOnHotModuleReload === 'function' for the duck typing? That's how Thenables work, afaik.
| const esmHmrIsPresent = !!(import.meta as HotImportMeta).hot; | ||
| /** | ||
| * This code shouldn't be imported in prod, but if it is, try to give any | ||
| * bundler as many chances as it can to dead code eliminate it. |
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From what I've seen, the DEC is often weak and I'm not sure it'll always propagate out of statements like this. You might have a better chance if this is in the if clause below. Over time it'd be good to document here that this was tested in which tools.
| const implMap = new Map<string, HotReloadableElementClass>(); | ||
| const hotDefine: typeof customElements.define = function hotDefine( | ||
| tagname, classObj) { | ||
| if (!isHotReloadableElementClass(classObj)) { |
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You may want to consider eventually adding some support for elements without this callback - maybe proxy the class so that new instances are created with the new class, or so the prototype is swapped out. This could be an opt-in workaround against some environments that try to do hot reloads by default, and maybe it'd do something kind of useful?
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Yeah, figuring out how best to leverage proxies here is definitely on the list of things to do here
| * @param updatedClass The newer version of this class | ||
| * (or some other class that's trying to claim this class' tagname). | ||
| */ | ||
| notifyOnHotModuleReload( |
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I would consider naming this with a Callback suffix like the lifecycle callbacks.
| @@ -0,0 +1,28 @@ | |||
| BSD 3-Clause License | |||
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| Copyright (c) 2019, The Polymer Authors. All rights reserved. | |||
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| Copyright (c) 2019, The Polymer Authors. All rights reserved. | |
| Copyright (c) 2020, The Polymer Authors. All rights reserved. |
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Do you guys plan to merge this any soon? |
This just provides the interface that overrides customElements.define. My thinking is that the LitElement implementation of
notifyOnHotModuleReloadwould live (and be tested) in the lit-element repo, as it needs to access private internals of LitElement.