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    1.1.0 • Public • Published

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    Lightweight TypeScript RemoteData implementation


    npm install @abraham/remotedata


    Read Slaying a UI Antipattern with Web Components (and TypeScript) for a more thorough guide.

    This is an example class that gets a tweet (type Status) from a remote HTTP API.

    import { Failure, fold, Initialized, Pending, RemoteData, Success } from '@abraham/remotedata';
    import { Status } from 'twitter-d';
    // Define what the RemoteData Failure and Success types will be.
    type State = RemoteData<number, Status>;
    class Thing {
      // Set the initial state as Initialized.
      private state: State = new Initialized();
      constructor() {
        // On instantiation start the remote call and render the current state.
      private async function getStatus() {
        // Before starting the remote call set the current state to Pending.
        this.state = new Pending();
        // Perform the actual remote request.
        const response = await fetch('https://api.example.com/tweet');
        if (response.ok) {
          // If the request succeeds set the state to Success with the returned data.
          const status: Status = await response.json();
          this.state = new Success(status);
        } else {
          // If the request does not succeed set the state to Failure with the reason.
          this.state = new Failure(status_code);
        // Render the new state.
      private get view(state: State): (state: State) => string {
        // Use `fold` to easily define logic based on the current state.
        // Fold takes four methods as parameters in the order of Initialized, Pending, Failure, and
        // Success and returns a method that takes a `RemoteData` state instance as a parameter. When
        // the returned method gets called with a `RemoteData` state, the method matching the correct
        // state gets called.
        return fold<string, number, Status>(
          // What to do if the state is Initialized.
          () => 'Initialized',
          // What to do if the request is Pending.
          () => 'Loading...',
          // What to do if the request fails.
          (error: number) => `Error: ${error}`,
          // What to do if the request succeeds.
          (status: Status) => `Got tweet from ${status.screen_name}`,
      private render(): string {
        // Render the current state in your UI.
        // `this.view` returns a method which is executed with the current state as a parameter.
        const text: string = this.view(this.state);
        // Maybe put it in a template.

    Using included type guards.

    import { RemoteData } from '@abraham/remotedata';
    import { Status } from 'twitter-d';
    import { getState } from './state';
    // Define what the RemoteData Failure and Success types will be.
    type State = RemoteData<number, Status>;
    const state: State = getState();
    if (isSuccess(state)) {
      // state is known to be of type Success<Status>



    npm i @abraham/remotedata

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