Neurotic and Probably Misinformed

    promise-sugar

    2.3.3 • Public • Published

    Promise syntactic sugar Build Status

    No need to write .then in your promise chains. The promise is the .then function itself!

    What it does

    1 ) It allows you to convert this

    Promise.resolve(10)
    .then((n) => n / 2)
    .then((n) => n * 3)
    .then(log) // -> 15
    .catch(logError)

    into this

    sweeten(10)
    ((n) => n / 2)
    ((n) => n * 3)
    (log) // -> 15
    (null, logError) // or .catch(logError)

    2 ) and this

    // Given two existing promises A and B
    // wait for A and B and return B's value
    log(await A.then(() => B)) // -> B's value

    into this

    log(await A(B)) // -> B's value

    where

    const log      = console.log.bind(console);
    const logError = console.error.bind(console);

    That's almost it! For More sugar see below.

    A sweeten promise is still a thenable. Thus you can still await for it, or you could swap the Promise with the sweeten version in your old code and it should still work the same.

    Promise-sugar tries to preserve all other behaviors of the Promise library used.

    There is another library that implements a similar paradigm - thunks.

    Thunks is different from Promise-sugar and more complex (a thunk is not a promise and it has no .catch() method).

    You can play with it on jsBin

    Install

    • Copy promise-sugar.js to your project or install it using npm:
    npm install promise-sugar --save
    • Import promise-sugar.js into your app using import (ESM), require (AMD or CommonJs) or as a script tag.
    import sweeten from 'promise-sugar';
    const sweeten = require('promise-sugar');
    <script src="https://unpkg.com/promise-sugar"></script>
    • Make sure there is a Promise implementation or get a polyfill like es6-promise.
    sweeten.usePromise(require('es6-promise').Promise); // polyfill

    More sugar

    Regardless of the Promise implementation used, all sweeten promises have the following methods:

    sweeten(promise)
        .catch(onReject)   // Promite/A+
        .finally(callback) // not a Promise/A+ method
        .timeout(1000)     // reject in 1 sec, not a Promise/A+ method

    If Promise.prototype.progress is defined, Promise-sugar will preserve it.

    Here are some helper methods of Promise-sugar:

    sweeten.when(value_or_thenable); // creates a sweeten promise
    let deferred = sweeten.defer();  // creates a deferred with a sweeten .promise
    
    sweeten.allValues(obj);          // Similar to Promise.all(list), but accepts an object with thenable values
    
    if(sweeten.isThenable(any)) any.then(doStuff);
    
    let waiter = sweeten.wait(123);  // setTimeout()
    waiter.then(doStuffLater);
    waiter.stop();                   // don't doStuffLater() (like clearTimeout())
    
    
    function sum(a,b) { return a + b; }
    let ssum = sweeten.fn(sum); // sweeten version of sum()
    ssum(2, Promise.resolve(3))(log); // -> 5
    
    
    // Promise/A+ sweet equivalents
    sweeten.resolve(val)
    sweeten.reject(val)
    sweeten.race(list)
    sweeten.all(list)
    sweeten.any(list)
    sweeten.allSettled(list)

    Examples

    Sweeten promises are just promises and functions (thens) at the same time:

    let result = sweeten(fetch('/my/api'))
                 ((res) => res.json())
    ;
    
    // Now you have a simple function that contains your result
    result(log);
    
    // and it is still a promise!
    result.catch(logError);
    
    // and can be used as such
    Promise.all([result, fetch('my/api/something/else')])
    .then(/*...*/);
    
    // or equivalent of the above
    sweeten.all([result, fetch('my/api/something/else')])
    (/*...*/);

    Sweeten promise constructor:

    let myStuff = new sweeten(function (resolve, rejext){
        setTimeout(resolve, 100, Math.random());
    });
    
    myStuff((myNumber) => {/*...*/}, (error) => {/*...*/});

    Install

    npm i promise-sugar

    DownloadsWeekly Downloads

    12

    Version

    2.3.3

    License

    MIT

    Unpacked Size

    69.3 kB

    Total Files

    12

    Last publish

    Collaborators

    • duzun