react-promiseful

A React component and hook to render children conditionally based on a promise status.

Installation

$ npm install react-promiseful

This library is written in modern JavaScript and is published in both CommonJS and ES module transpiled variants. If you target older browsers please make sure to transpile accordingly.

Demo

You may see a simple demo of react-promiseful in https://moxystudio.github.io/react-promiseful.

Usage

With <PromiseState> component:

import React, { useMemo, useState } from 'react';
import { PromiseState } from 'react-promiseful';

const SomeComponent = (props) => {
    const [savePromise, setSavePromise] = useState();
    const handleSave = useMemo(
        () => () => setSavePromise(props.save()),
        [props.save]
    );

    return (
        <div>
            <button disabled={ saveState.status === 'pending' } onSave={ handleSave }>
                Save
            </button>

            <PromiseState promise={ savePromise }>
                { (saveState) => (
                    <p>
                        { saveState.status === 'pending' && 'Saving...' }
                        { saveState.status === 'fulfilled' && 'Saved!' }
                        { saveState.status === 'rejected' && 'Oops, failed to save' }
                    </p>
                ) }
            </PromiseState>
        </div>
    );
}

With usePromiseState() hook:

import React, { useMemo, useState } from 'react';
import { usePromiseState } from 'react-promiseful';

const SomeComponent = (props) => {
    const [savePromise, setSavePromise] = useState();
    const saveState = usePromiseState(savePromise);
    const handleSave = useMemo(
        () => () => setSavePromise(props.save()),
        [props.save]
    );

    return (
        <div>
             <button disabled={ saveState.status === 'pending' } onSave={ handleSave }>
                Save
            </button>

            <p>
                { saveState.status === 'pending' && 'Saving..' }
                { saveState.status === 'fulfilled' && 'Saved!' }
                { saveState.status === 'rejected' && 'Oops, failed to save' }
            </p>
        </div>
    );
}

API

• <PromiseState>
• usePromiseState(promise, [options])
• getPromiseState(promise)

PromiseState

The <PromiseState> component allows you to conditionally render children based on the promise status and fulfillment/rejection value. It leverages the render props technique to know what to render.

Props

promise

Type: Promise

The promise to observe.

children

A render prop function with the following signature:

(state) => {}

The state argument is an object that contains the following properties:

• status is one of none (when there's no promise), pending, rejected, fulfilled
• value is either the fulfillment value or the rejection value
• withinThreshold indicating if we are still within the configured thresholdMs

thresholdMs

Type: number
Default: 0

The timespan in ms to consider the promise within the threshold. Useful if you want to render a loading only when the promise is taking some time.

The state will contain a withinThreshold boolean property for you to use in the children render prop. Moreover, you may also use "withinThreshold" variants in the statusMap and onSettleDelay props.

statusMap

Type: Object

An object to map statuses, useful when you want to use other names:

{
    pending: 'loading',
    fulfilled: 'success',
    rejected: 'error',
}

When the thresholdMs prop is used, you are also able to map the "withinThreshold" variants. This is useful if you want to hide visual feedback that is too quick. For instance, to avoid having any spinners and success feedback within the threshold:

{
    pendingWithinThreshold: 'none',
    fulfilledWithinThreshold: 'none',
    pending: 'loading',
    fulfilled: 'success',
    rejected: 'error',
}

You may omit statuses you don't want to map and the default ones will be used. Moreover, if no "withinThreshold" statuses are defined, their normal counterparts will be used.

onSettle

Type: Function

A callback to be called whenever the promise fulfills or rejects. It receives the state as argument:

(state) => {}

This is useful to trigger a change in a user-interface after the promise resolves:

const handleSettle = ({ status }) => {
    if (status === 'fulfilled') {
        complete(); // Imaginary function that completes the operation in the UI
    }
};

onSettledDelayMs

Type: number, Object
Default: 0

The delay before calling onSettle. This is useful if you have success animations that must complete before triggering a change in the user-interface.

You may either specify a number to signal the same delay for both fulfilled and rejected statuses or an object containing the granular delays:

{
    fulfilled: 2000,
    rejected: 2000,
}

When the thresholdMs prop is used, you are also able to also map the "withinThreshold" variants. For instance, you may want the callback to be called with a delay, except when there is no visual-feedback:

{
    fulfilledWithinThreshold: 0,
    fulfilled: 2000,
    rejected: 2000,
}

You may omit delays you don't want to map and the default ones will be used. Moreover, if no "withinThreshold" statuses are defined, their normal counterparts will be used.

usePromiseState(promise, [options])

The hook version of the <PromiseState> component. The options available to both are exactly the same.

const promiseState = usePromiseState(somePromise);

The returned value from the hook is the promise state, an object that contains the following properties:

• status is one of none (when there's no promise), pending, rejected, fulfilled
• value is either the fulfillment value or the rejection value
• withinThreshold indicating if we are still within the configured thresholdMs

getPromiseState(promise)

Returns the current promise state, an object with status and value.

If the promise was yet not used in <PromiseState> or usePromiseState(), the promise state will be pending.

Tests

$ npm test
$ npm test -- --watch # during development

License

Released under the MIT License.