@wordpress/core-data
Version:
Access to and manipulation of core WordPress entities.
31 lines (29 loc) • 984 B
JavaScript
/** @typedef {import('../types').AnyFunction} AnyFunction */
/**
* Higher-order reducer creator which creates a combined reducer object, keyed
* by a property on the action object.
*
* @param {string} actionProperty Action property by which to key object.
*
* @return {AnyFunction} Higher-order reducer.
*/
export const onSubKey = actionProperty => reducer => (state = {}, action) => {
// Retrieve subkey from action. Do not track if undefined; useful for cases
// where reducer is scoped by action shape.
const key = action[actionProperty];
if (key === undefined) {
return state;
}
// Avoid updating state if unchanged. Note that this also accounts for a
// reducer which returns undefined on a key which is not yet tracked.
const nextKeyState = reducer(state[key], action);
if (nextKeyState === state[key]) {
return state;
}
return {
...state,
[key]: nextKeyState
};
};
export default onSubKey;
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