react/packages/shared/forks/ReactFeatureFlags.www.js

68 lines
2.1 KiB
JavaScript

/**
* Copyright (c) 2013-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @flow
*/
import typeof * as FeatureFlagsType from 'shared/ReactFeatureFlags';
import typeof * as FeatureFlagsShimType from './ReactFeatureFlags.www';
// Re-export dynamic flags from the www version.
export const {
enableSuspense,
debugRenderPhaseSideEffects,
debugRenderPhaseSideEffectsForStrictMode,
enableGetDerivedStateFromCatch,
replayFailedUnitOfWorkWithInvokeGuardedCallback,
warnAboutDeprecatedLifecycles,
} = require('ReactFeatureFlags');
// The rest of the flags are static for better dead code elimination.
export const warnAboutLegacyContextAPI = __DEV__;
// In www, we have experimental support for gathering data
// from User Timing API calls in production. By default, we
// only emit performance.mark/measure calls in __DEV__. But if
// somebody calls addUserTimingListener() which is exposed as an
// experimental FB-only export, we call performance.mark/measure
// as long as there is more than a single listener.
export let enableUserTimingAPI = __DEV__;
export const enableProfilerTimer = __PROFILE__;
let refCount = 0;
export function addUserTimingListener() {
if (__DEV__) {
// Noop.
return () => {};
}
refCount++;
updateFlagOutsideOfReactCallStack();
return () => {
refCount--;
updateFlagOutsideOfReactCallStack();
};
}
// The flag is intentionally updated in a timeout.
// We don't support toggling it during reconciliation or
// commit since that would cause mismatching user timing API calls.
let timeout = null;
function updateFlagOutsideOfReactCallStack() {
if (!timeout) {
timeout = setTimeout(() => {
timeout = null;
enableUserTimingAPI = refCount > 0;
});
}
}
// Flow magic to verify the exports of this file match the original version.
// eslint-disable-next-line no-unused-vars
type Check<_X, Y: _X, X: Y = _X> = null;
// eslint-disable-next-line no-unused-expressions
(null: Check<FeatureFlagsShimType, FeatureFlagsType>);