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    @r/middleware

    0.8.1 • Public • Published

    r/middleware

    Helpful Redux middleware

    Installation

    Install via npm.

    npm install -S @r/middleware

    Modules

    @r/middleware exports two middlewares: Thunker and PromiseWell;

    Thunker

    Thunker expands on a traditional Redux thunk utility. Namely, it requires that the thunking action returns a promise. As a result, it becomes easier to know when the thunked actions have completed: when the promise resolves, all thunked actions have fired.

    // Initializing a Thunker
    import Thunker from '@r/middleware/Thunker';
    
    const thunk = Thunker.create();
    
    // in Redux
    applyMiddleware(..., thunk, ...);

    To simplify using Thunker, it is highly recommended es7 style async functions are used.

    // example thunked action
    
    const getData = () => async (dispatch, getState, utils) => {
      // immediately dispatch synchronous actions as normal
      dispatch(/* sync action */);
    
      // wait for data if need be
      const { foo, bar } = await asyncFunctionCall();
    
      // continue to dispatch as normal
      dispatch(/* another action */);
    };

    Thunker performs an additional task. Many times, it becomes necessary to wait for some piece of state to update, or to wait for a particular action to be dispatched before another action is dispatched. Thunker solves this by surfacing two utility methods: waitForState and waitForAction. Both return a promise that can be await-ed on.

    waitForState

    waitForState(stateFn: Function, cb: Function [, stateFailedFn: Function]): Promise
    

    stateFn(state: Object): Boolean

    A function that creates the condition that must be met for the callback to fire. Receives a copy of state as its argument. Expected to return a truthy/falsey value.

    cb(state: Object): void

    A function that is called when the conditional is met. Receives a copy of state as its argument.

    stateFailedFn(state: Object): void (OPTIONAL)

    A function that is called the first time the conditional is not met. Only fires once. Receives a copy of state as its argument.

    waitForAction

    waitForAction(actionFn: Function, cb: Function): Promise
    

    actionFn: Function(action: Object)

    A function that receives a Redux action, represents the condition that must be met for the callback to fire. After waitForAction is invoked, if action is dispatched, the callback will fire.

    cb(state: Object): void

    A function that is called when the action is dispatched. Receives a copy of state as its argument.

    PromiseWell

    The PromiseWell merely collects promises that dispatched by other middleware. It should be one of the last middleware invoked.

    // Initializing a PromiseWell
    import PromiseWell from '@r/middleware/PromiseWell';
    
    const well = PromiseWell.create();
    
    // in Redux
    applyMiddleware(..., well.middleware, ...);
    
    // on the server side
    await well.onComplete();

    In addition to capturing promises, the PromiseWell lets you query to check if all the captured promises have been completed through the use of onComplete.

    Install

    npm i @r/middleware

    DownloadsWeekly Downloads

    27

    Version

    0.8.1

    License

    MIT

    Last publish

    Collaborators

    • redditnpm2
    • schwers
    • madlee
    • wick