Already Figured Out State

A convenient library for managing centralized state in Typescript/JS

Reducer Helper Functions

InsertOrUpdate

    const state = {
        entities: {
        1: { id: 1, name: "one" },
        3: { id: 3, name: "three" },
        },
        order: [1, 3],
    };

    const newObject = { id: 2, name: "two" };
    const newState = insertOrUpdate(
        state,
        newObject
    );

newState will now be:

{
        entities: {
        1: { id: 1, name: "one" },
        3: { id: 3, name: "three" },
        2: newObject,
        },
        order: [1, 3, 2],
    }

InsertOrUpdateMultiple

    const state = {
        entities: {
        1: { id: 1, name: "one" },
        3: { id: 3, name: "three" },
        },
        order: [1, 3],
    };

    // object with id 2 does not exist yet
    const newObject = { id: 2, name: "two" };

    // object id 1 already exists in the store
    const updatedObject = { id: 1, name: "Fancy new title" };
    const newState = insertOrUpdateMultiple(
        state,
        [newObject, updatedObject]
    );

newState will now be:

{
        entities: {
        1: { id: 1, name: "Fancy new title" },
        3: { id: 3, name: "three" },
        2: { id: 2, name: "two" },
        },
        order: [1, 3, 2],
    }

Selector Functions

selectById

selectById will select entities by their id. If you only pass a single id (not wrapped in an array) it will return a single object. Note that this behavior does not apply to other select functions, because no other key is unique

const state = {
entities: {
1: { id: 1, name: "one" },
2: { id: 2, name: "two" },
3: { id: 3, name: "three" },
},
order: [1, 2, 3],
};

// returns { id: 1, name: "one" }
const singleResultId = selectById(state, 1);


// returns [ { id: 2, name: "two" }, { id: 3, name: "three" } ]
const multiIdResult = selectById(state, [2,3]);


// returns undefined
const noResult = selectByFunction(state, 5);

selectByProp

selectByProp will select from the store according to a filter function. The function receives the object, the larger store, and the index of the object in the order

const state = {
entities: {
1: { id: 1, name: "one" },
2: { id: 2, name: "two" },
3: { id: 3, name: "three" },
},
order: [1, 2, 3],
};

// returns [{ id: 1, name: "one" }]
const singleResultId = selectByProp(state, id, 1);


// returns [ { id: 2, name: "two" }, { id: 3, name: "three" } ]
const multiplePropValues = selectByProp(state, "name", ["two","three"]);


// returns []
const noResult = selectByProp(state, ({ id }) => id == 5);

selectByFunction

selectByFunction will select from the store according to a filter function. The function receives the object, the larger store, and the index of the object in the order

const state = {
entities: {
1: { id: 1, name: "one" },
2: { id: 2, name: "two" },
3: { id: 3, name: "three" },
},
order: [1, 2, 3],
};

// returns [{ id: 1, name: "one" }]
const singleResultId = selectByFunction(state, ({ id }) => id == 1);


// returns [ { id: 2, name: "two" }, { id: 3, name: "three" } ]
const multiResult = selectByFunction(state, ({ id }) => id > 1);


// returns []
const noResult = selectByFunction(state, ({ id }) => id == 5);