promise-thunk

promise-thunk - npm

ES6 Promise + Thunk = PromiseThunk!

promise-thunk is standard ES6 Promise implementation + thunk.
it supports browsers and node.js.

it throws unhandled rejection error.

INSTALL:

for node.js:

$ npm install promise-thunk --save

or

for browsers:

https://lightspeedworks.github.io/promise-thunk/promise-thunk.js

<script src="https://lightspeedworks.github.io/promise-thunk/promise-thunk.js"></script>

PREPARE:

you can use PromiseThunk.

in node.js

var PromiseThunk = require('promise-thunk');

in browsers

(function (PromiseThunk) {
  'use strict';
  // you can use PromiseThunk
})(this.PromiseThunk || require('promise-thunk'));

or

var PromiseThunk = this.PromiseThunk || require('promise-thunk');

QUICK EXAMPLE:

var PromiseThunk = require('promise-thunk');

function sleepNodeStyle(msec, val, cb) {
  console.log(val + ' timer start: ' + msec);
  setTimeout(function () {
    console.log(val + ' timer end  : ' + msec);
    cb(null, val);
  }, msec);
}

var sleepPromiseThunk = PromiseThunk.wrap(sleepNodeStyle);

// promise type
sleepPromiseThunk(1000, 'a1')
.then(
  function (val) {
    console.log('a2 val: ' + val);
    return sleepPromiseThunk(1000, 'a2'); },
  function (err) { console.log('err:' + err); })
.catch(
  function (err) { console.log('err:' + err); }
);

// thunk type
sleepPromiseThunk(1000, 'b1')
(function (err, val) {
  console.log('b2 val: ' + val + (err ? ' err: ' + err : ''));
  return sleepPromiseThunk(1000, 'b2'); })
(function (err, val) {
  console.log('b3 val: ' + val + (err ? ' err: ' + err : '')); });

// mixed promise and thunk type
sleepPromiseThunk(1000, 'c1')
(function (err, val) {
  console.log('c2 val: ' + val + (err ? ' err: ' + err : ''));
  return sleepPromiseThunk(1000, 'c2'); })
.then(
  function (val) {
    console.log('c3 val: ' + val);
    return sleepPromiseThunk(1000, 'c3'); },
  function (err) { console.log('err:' + err); });

//output:
// a1 timer start: 1000
// b1 timer start: 1000
// c1 timer start: 1000
// a1 timer end  : 1000
// a2 val: a1
// a2 timer start: 1000
// b1 timer end  : 1000
// b2 val: b1
// b2 timer start: 1000
// c1 timer end  : 1000
// c2 val: c1
// c2 timer start: 1000
// a2 timer end  : 1000
// b2 timer end  : 1000
// b3 val: b2
// c2 timer end  : 1000
// c3 val: c2
// c3 timer start: 1000
// c3 timer end  : 1000

USAGE:

PromiseThunk Specification

new PromiseThunk(setup)

how to make promise.

p = new PromiseThunk(
  function setup(resolve, reject) {
    // async process -> resolve(value) or reject(error)
    try { resolve('value'); }
    catch (error) { reject(error); }
  }
);
// setup(
//  function resolve(value) {},
//  function reject(error) {})

example

var p = new PromiseThunk(
  function setup(resolve, reject) {
    setTimeout(function () {
      if (Math.random() < 0.5) resolve('value');
      else reject(new Error('error'));
    }, 100);
  }
);

// promise
p.then(
  function (val) { console.info('val:', val); },
  function (err) { console.error('err:', err); });

// thunk
p(function (err, val) { console.info('val:', val, 'err:', err); });

// mixed chainable
p(function (err, val) { console.info('val:', val, 'err:', err); })
(function (err, val) { console.info('val:', val, 'err:', err); })
(function (err, val) { console.info('val:', val, 'err:', err); })
.then(
  function (val) { console.info('val:', val); },
  function (err) { console.error('err:', err); })
.then(
  function (val) { console.info('val:', val); },
  function (err) { console.error('err:', err); })
(function (err, val) { console.info('val:', val, 'err:', err); })
.then(
  function (val) { console.info('val:', val); },
  function (err) { console.error('err:', err); });

PromiseThunk.convert(p)

convert() converts standard promise to promise-thunk.

• p: standard promise or thenable object.

PromiseThunk.promisify([ctx,] fn, [options])

promisify() converts node style function into a function returns promise-thunk.
you can use fs.exists() and child_process.exec() also.

• ctx: context object. default: this or undefined.
• fn: node-style normal function.
• options: options object.
  • context: context object.

also thenable, yieldable, callable.

postgres pg example:

var pg = require('pg');
var pg_connect = PromiseThunk.promisify(pg, pg.connect);         // -> yield pg_connect()
var client_query = PromiseThunk.promisify(client, client.query); // -> yield client_query()

PromiseThunk.promisify(object, method, [options])

promisify() defines method promisified function returns promise-thunk.

• object: target object.
• method: method name string.
• options: method name suffix or postfix. default: 'Async'. or options object.
  • suffix: method name suffix or postfix. default: 'Async'.
  • postfix: method name suffix or postfix. default: 'Async'.

postgres pg example:

var pg = require('pg');
PromiseThunk.promisify(pg, 'connect', {suffix: 'A'});             // -> yield pg.connectA()
PromiseThunk.promisify(pg.Client.prototype, 'connect'); // -> yield client.connectAsync()
PromiseThunk.promisify(pg.Client.prototype, 'query');   // -> yield client.queryAsync()

PromiseThunk.promisifyAll(object, [options])

promisifyAll() defines all methods promisified function returns promise-thunk.

• object: target object.
• options: method name suffix or postfix. default: 'Async'. or options object.
  • suffix: method name suffix or postfix. default: 'Async'.
  • postfix: method name suffix or postfix. default: 'Async'.

file system fs example:

var fs = require('fs');
PromiseThunk.promisifyAll(fs, {suffix: 'A'});  // -> yield fs.readFileA()

postgres pg example:

var pg = require('pg');
PromiseThunk.promisifyAll(pg.constructor.prototype, {suffix: 'A'});  // -> yield pg.connectA()
PromiseThunk.promisifyAll(pg.Client.prototype);  // -> yield client.connectAsync()
                                    // -> yield client.queryAsync()

PromiseThunk.thunkify([ctx,] fn, [options])

thunkify() converts node style function into a thunkified function.
you can use fs.exists() and child_process.exec() also.

• ctx: context object. default: this or undefined.
• fn: node-style normal function with callback.
• options: options object.
  • context: context object.

also yieldable, callable.

postgres pg example:

var pg = require('pg');
var pg_connect = thunkify(pg, pg.connect);         // -> yield pg_connect()
var client_query = thunkify(client, client.query); // -> yield client_query()

PromiseThunk.thunkify(object, method, [options])

thunkify() defines method thunkified function returns thunk.

• object: target object.
• method: method name string.
• options: method name suffix or postfix. default: 'Async'. or options object.
  • suffix: method name suffix or postfix. default: 'Async'.
  • postfix: method name suffix or postfix. default: 'Async'.

postgres pg example:

var pg = require('pg');
PromiseThunk.thunkify(pg, 'connect', {suffix: 'A'});  // -> yield pg.connectA()
PromiseThunk.thunkify(pg.Client.prototype, 'connect'); // -> yield client.connectAsync()
PromiseThunk.thunkify(pg.Client.prototype, 'query');   // -> yield client.queryAsync()

PromiseThunk.thunkifyAll(object, [options])

thunkifyAll() defines all methods thunkified function returns thunk.

• object: target object.
• options: method name suffix or postfix. default: 'Async'. or options object.
  • suffix: method name suffix or postfix. default: 'Async'.
  • postfix: method name suffix or postfix. default: 'Async'.

file system fs example:

var fs = require('fs');
PromiseThunk.thunkifyAll(fs, {suffix: 'A'});  // -> yield fs.readFileA()

postgres pg example:

var pg = require('pg');
PromiseThunk.thunkifyAll(pg.constructor.prototype, {suffix: 'A'});  // -> yield pg.connectA()
PromiseThunk.thunkifyAll(pg.Client.prototype);  // -> yield client.connectAsync()
                                                // -> yield client.queryAsync()

promise.then(onFulfilled, onRejected)

how to use promise.

p = p.then(
  function resolved(value) {},
  function rejected(error) {});

example

p = p.then(
  function resolved(value) {
    console.info(value);
  },
  function rejected(error) {
    console.error(error);
  });

promise.catch(onRejected)

how to catch error from promise.

p = p.catch(
  function rejected(error) {});

or

when you use old browser

p = p['catch'](
  function rejected(error) {});

PromiseThunk.all(iterable or array)

wait for all promises.

p = PromiseThunk.all([promise, ...]);

PromiseThunk.race(iterable or array)

get value or error of first finished promise.

p = PromiseThunk.race([promise, ...]);

PromiseThunk.resolve(value or promise)

get resolved promise.

p = PromiseThunk.resolve(value or promise);

PromiseThunk.reject(error)

get rejected promise.

p = PromiseThunk.reject(error);

PromiseThunk.accept(value)

get resolved (accepted) promise.

p = PromiseThunk.accept(value);

PromiseThunk.defer()

make deferred object with promise.

dfd = PromiseThunk.defer();
// -> {promise, resolve, reject}

SEE ALSO:

npm promise-light

npm aa

npm co

LICENSE:

MIT