feat: add flag to disable synthetic shadow #4408
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| // Note that lwcRuntimeFlags must be referenced as a pure global, or else string replacement in ESBuild | ||
| // will not work. But we also have to check to make sure that lwcRuntimeFlags is defined, so this | ||
| // `Object.defineProperty` code is copied from @lwc/features itself. | ||
| banner += ` | ||
| if (!globalThis.lwcRuntimeFlags) { | ||
| Object.defineProperty(globalThis, 'lwcRuntimeFlags', { value: Object.create(null) }); | ||
| } | ||
| if (!lwcRuntimeFlags.ENABLE_FORCE_SHADOW_MIGRATE_MODE) { | ||
| if (!lwcRuntimeFlags.ENABLE_FORCE_SHADOW_MIGRATE_MODE && !lwcRuntimeFlags.DISABLE_SYNTHETIC_SHADOW) { |
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Not every environment has the runtime flag set before @lwc/synthetic-shadow executes, but enough do that it makes sense to just disable synthetic shadow entirely in those cases.
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Sorry, I completely missed this part in the initial pass. The logic we're adding to computeShadowMode is unnecessary for applications that set feature flags before bootstrap, correct?
Feature flags being available before LWC bootstraps was assumed in the initial feature flag design. We really shouldn't be having to consider other cases...
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Unfortunately there are still apps that don't set flags before LWC bootstraps. Ideally yes we would not need this code, but this is the next-best thing.
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We basically support two flavors of native shadow--the first is via polyfill exclusion (not using @lwc/synthetic-shadow) and the second is via mixed mode. This change feels more in line with the latter as we're still operating in the context of synthetic shadow polyfills. Should it instead be called FORCE_MIXED_MODE or something similar?
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How about |
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I completely missed the part where we actually prevent |
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/nucleus test |
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Well that's strange! A workflow could not be found for this PR. Please try running the |
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/nucleus start |
Details
Today, you can simply not import
@lwc/synthetic-shadowand you'll run in pure-native-shadow mode. However, if@lwc/synthetic-shadowis loaded, then there's no way to switch back to a pure-native-shadow mode.In some environments though (notably core), it would be convenient to have a runtime flag that can toggle this behavior on-demand, regardless of whether
@lwc/synthetic-shadowwas previously loaded or not. This PR accomplishes that via a newlwcRuntimeFlagsprop.Does this pull request introduce a breaking change?
Does this pull request introduce an observable change?