@react-navigation/core/lib/commonjs/useIsFocused.js

Core utilities for building navigators

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = useIsFocused;
var React = _interopRequireWildcard(require("react"));
var _useNavigation = _interopRequireDefault(require("./useNavigation"));
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
function _getRequireWildcardCache(nodeInterop) { if (typeof WeakMap !== "function") return null; var cacheBabelInterop = new WeakMap(); var cacheNodeInterop = new WeakMap(); return (_getRequireWildcardCache = function (nodeInterop) { return nodeInterop ? cacheNodeInterop : cacheBabelInterop; })(nodeInterop); }
function _interopRequireWildcard(obj, nodeInterop) { if (!nodeInterop && obj && obj.__esModule) { return obj; } if (obj === null || typeof obj !== "object" && typeof obj !== "function") { return { default: obj }; } var cache = _getRequireWildcardCache(nodeInterop); if (cache && cache.has(obj)) { return cache.get(obj); } var newObj = {}; var hasPropertyDescriptor = Object.defineProperty && Object.getOwnPropertyDescriptor; for (var key in obj) { if (key !== "default" && Object.prototype.hasOwnProperty.call(obj, key)) { var desc = hasPropertyDescriptor ? Object.getOwnPropertyDescriptor(obj, key) : null; if (desc && (desc.get || desc.set)) { Object.defineProperty(newObj, key, desc); } else { newObj[key] = obj[key]; } } } newObj.default = obj; if (cache) { cache.set(obj, newObj); } return newObj; }
/**
 * Hook to get the current focus state of the screen. Returns a `true` if screen is focused, otherwise `false`.
 * This can be used if a component needs to render something based on the focus state.
 */
function useIsFocused() {
  const navigation = (0, _useNavigation.default)();
  const [isFocused, setIsFocused] = (0, React.useState)(navigation.isFocused);
  const valueToReturn = navigation.isFocused();
  if (isFocused !== valueToReturn) {
    // If the value has changed since the last render, we need to update it.
    // This could happen if we missed an update from the event listeners during re-render.
    // React will process this update immediately, so the old subscription value won't be committed.
    // It is still nice to avoid returning a mismatched value though, so let's override the return value.
    // This is the same logic as in https://github.com/facebook/react/tree/master/packages/use-subscription
    setIsFocused(valueToReturn);
  }
  React.useEffect(() => {
    const unsubscribeFocus = navigation.addListener('focus', () => setIsFocused(true));
    const unsubscribeBlur = navigation.addListener('blur', () => setIsFocused(false));
    return () => {
      unsubscribeFocus();
      unsubscribeBlur();
    };
  }, [navigation]);
  React.useDebugValue(valueToReturn);
  return valueToReturn;
}
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