redux-sac

redux-sac

Slice and compose redux-type reducers.

subReducer(key, reducer, additionalKey, ...)

Creates a wrapper reducer that call reducer on the substate specified by key. You may use dot notation. Rest of the state is left untouched.

	const r = subReducer("persons", personReducer);

    r({persons: ["John", "Jill"], cars: ["Honda"]}, cityon);
    // => {
    //   persons: personReducer(["John", "Jill"], action), 
    //   cars: ["Honda"]
    // }

Respects redux convention that if no change was made, the identical object should be returned. So in previous case, if personReducer would return the identical array, r would return the state object it was passed in.

If persons were deeper in hierarchy, it could have been created as const r = subReducer("files.persons", personReducer); for example.

You may pass additional keys (also with possible dot-notation) as addition arguments. In that case, additional parts of state will be fetched and passed to a sub-reducer:

	const r = subReducer("persons", personReducer, "assets.cars");

    r({persons: ["John", "Jill"], assets: {cars: ["Honda"]}}, action);
    // => {
    //   persons: personReducer(["John", "Jill"], action, ["Honda"]), 
    //   assets: {cars: ["Honda"]}
    // }

This technique is mentioned in Redux docs, in "Beyond combineReducers" page.

composeReducers(reducer1, reducer2, ...)

Creates a wrapper reducer that calls passed reducers one after another, passing intermediate states. and returning the result of the last one.

Useful to "concatenate" a few subReducers. like:

	composeReducers(
	    subReducer("files.persons", personReducer, "assets.swag"),
	    subReducer("files.clients", clientReducer, "news"),
	    subReducer("assets", assetReducer),
	    baseReducer
	)

cowValueModel(key)

Creates an object with set of functions allowing to set or get specified key from any object. You can use dot notation.

Setting return a copy with specified (sub-)property changed; in case no change actually happens, returns the original object.

    const name = cowValueModel("name");
    
    name.get({name: "Tom"});
    // => "Tom"
    name.set({name: "Tom"}, "Jerry");
    // => {name: "Jerry"}
    
    const city = cowValueModel("address.city");
    const object = {address: {city: "New York"}};
    
    city.get(object);
    // => "New York"
    city.set(object, "London");
    // => {address: {city: "London"}}
    object;
    // => {address: {city: "New York"}}
    city.set(object, "New York") === object;
    // => true