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    @momsfriendlydevco/express-middleware-promise

    0.0.0 • Public • Published

    Express-Middleware-Promise

    A simple wrapper around Express to make it promise compatible.

    • Completely Promise library agnostic - Use native promises, Q, Bluebird or whatever library you want
    • Backwards compatible - Mix and match callbacks and promises as needed
    • Low overhead - While this library does have to wrap all middleware calls the codebase is minimal to prevent drag
    var express = require('express');
    var expressPromises = require('@momsfriendlydevco/express-middleware-promise');
    
    var app = express();
    expressPromises(app);
    
    
    // Any simple return value gets sent via res.send() automatically
    app.get('/api/hello-world', ()=> 'Hello World!'); 
    
    // Use setTimeout to pause for 100 inside a promise
    app.get('/api/pause', ()=> new Promise(resolve => setTimeout(()=> resolve('I waited!'), 100)));
    
    // Make a middleware chain of promises
    app.get('/api/chain',
    	()=> BigComplexPromise(),
    	()=> AnotherComplexPromise(),
    	()=> YetAnotherPromise()
    );
    
    // Normal callback style express functions are still fully supported
    app.get('/api/classic', (req, res) => res.send('Old school!'));
    
    // Mix and match approches
    app.get('/api/mixed',
    	(req, res, next) => next(),
    	(req, res, next) => setTimeout(()=> next(), 10),
    	(req, res, next) => new Promise(resolve => setTimeout(()=> resolve(), 20)),
    	(req, res) => res.send('Done!'),
    );

    API

    Express-As-Promised exports one function which mutates the Express app object, replacing some built in functions so that promises are supported.

    The function can either be called with the entire Express object:

    var app = express();
    expressAsPromised(app);

    ... or with options:

    var app = express();
    expressAsPromised({
    	app: app,
    	setting1: settingValue,
    });

    Supported options are listed below.

    Option Type Default Description
    app Express App none The Express app object you want to mutate
    isPromise function(obj) (complex, see code) How to identify a promise return. By default this function checks that the passed object is an object and contains a then property
    isResolvable function(obj) (complex, see code) How to identify what responses should be resolved. Default is to identify a scalar result that looks like a JS native
    resolve function(req, res, data) (see code) When isResolvable passes, this function indicates how the response is output. Default is to use res.send() with some minor wrapping
    resolveEmpty function(req, res, data) res.sendStatus(200) How to resolve the last item in a middleware chain if no result has been provided
    error function(req, res, data) res.sendStatus(400).send(data) How to output caught errors
    wrapFunctions array ['delete', 'get', 'post', 'put'] What Express functions should be wrapped to add promise support

    Install

    npm i @momsfriendlydevco/express-middleware-promise

    DownloadsWeekly Downloads

    2

    Version

    0.0.0

    License

    MIT

    Unpacked Size

    8.24 kB

    Total Files

    4

    Last publish

    Collaborators

    • mr-yellow
    • melromero
    • hash-bang
    • 1watt
    • eekthecat