Data and service information in one capsule.

npm i kapsel

const kapsel = new Kapsel('Init Data');

kapsel.subscribe(({isLoading, data}) => {
    console.log({isLoading, data});
});

const provider = {
    get: () => {
      return new Promise((res) => setTimeout(() => res('Useful data'), 1000))
    }
};

kapsel.fill(provider.get());

// console.log shows:
// {isLoading: true, data: 'Init Data'}

// one second later console.log shows  
// {isLoading: false, data: 'Useful data'}

initial: any - default value

defer?: () => Promise<any> - will be called when the data is read for the first time. Works only one time

data: any - current data

prev: any - previous data

isLoading: boolean - is in the process of filling in

error: Error | null - filling process error

hasError: boolen - true if error not null

fill: (promise: Promise<any>) => void - method for filling with data

subscribe: (kapsel: Kapsel) => void - adds a callback that will be called for any state change

unsubscribe: (kapsel: Kapsel) => void - removes the callback