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Defined in node_modules/rsvp/lib/rsvp/all.js:3
This is a convenient alias for RSVP.Promise.all
.
Defined in node_modules/rsvp/lib/rsvp/all-settled.js:16
RSVP.allSettled
is similar to RSVP.all
, but instead of implementing a fail-fast method, it waits until all the promises have returned and shows you all the results. This is useful if you want to handle multiple promises' failure states together as a set.
Returns a promise that is fulfilled when all the given promises have been settled. The return promise is fulfilled with an array of the states of the promises passed into the promises
array argument.
Each state object will either indicate fulfillment or rejection, and provide the corresponding value or reason. The states will take one of the following formats:
{ state: 'fulfilled', value: value } or { state: 'rejected', reason: reason }
Example:
let promise1 = RSVP.Promise.resolve(1); let promise2 = RSVP.Promise.reject(new Error('2')); let promise3 = RSVP.Promise.reject(new Error('3')); let promises = [ promise1, promise2, promise3 ]; RSVP.allSettled(promises).then(function(array){ // array == [ // { state: 'fulfilled', value: 1 }, // { state: 'rejected', reason: Error }, // { state: 'rejected', reason: Error } // ] // Note that for the second item, reason.message will be '2', and for the // third item, reason.message will be '3'. }, function(error) { // Not run. (This block would only be called if allSettled had failed, // for instance if passed an incorrect argument type.) });
Defined in node_modules/rsvp/lib/rsvp/defer.js:3
RSVP.defer
returns an object similar to jQuery's $.Deferred
. RSVP.defer
should be used when porting over code reliant on $.Deferred
's interface. New code should use the RSVP.Promise
constructor instead.
The object returned from RSVP.defer
is a plain object with three properties:
RSVP.Promise
.promise
property on this object to become rejectedpromise
property on this object to become fulfilled.Example:
let deferred = RSVP.defer(); deferred.resolve("Success!"); deferred.promise.then(function(value){ // value here is "Success!" });
Defined in node_modules/rsvp/lib/rsvp/node.js:71
RSVP.denodeify
takes a 'node-style' function and returns a function that will return an RSVP.Promise
. You can use denodeify
in Node.js or the browser when you'd prefer to use promises over using callbacks. For example, denodeify
transforms the following:
let fs = require('fs'); fs.readFile('myfile.txt', function(err, data){ if (err) return handleError(err); handleData(data); });
into:
let fs = require('fs'); let readFile = RSVP.denodeify(fs.readFile); readFile('myfile.txt').then(handleData, handleError);
If the node function has multiple success parameters, then denodeify
just returns the first one:
let request = RSVP.denodeify(require('request')); request('http://example.com').then(function(res) { // ... });
However, if you need all success parameters, setting denodeify
's second parameter to true
causes it to return all success parameters as an array:
let request = RSVP.denodeify(require('request'), true); request('http://example.com').then(function(result) { // result[0] -> res // result[1] -> body });
Or if you pass it an array with names it returns the parameters as a hash:
let request = RSVP.denodeify(require('request'), ['res', 'body']); request('http://example.com').then(function(result) { // result.res // result.body });
Sometimes you need to retain the this
:
let app = require('express')(); let render = RSVP.denodeify(app.render.bind(app));
The denodified function inherits from the original function. It works in all environments, except IE 10 and below. Consequently all properties of the original function are available to you. However, any properties you change on the denodeified function won't be changed on the original function. Example:
let request = RSVP.denodeify(require('request')), cookieJar = request.jar(); // <- Inheritance is used here request('http://example.com', {jar: cookieJar}).then(function(res) { // cookieJar.cookies holds now the cookies returned by example.com });
Using denodeify
makes it easier to compose asynchronous operations instead of using callbacks. For example, instead of:
let fs = require('fs'); fs.readFile('myfile.txt', function(err, data){ if (err) { ... } // Handle error fs.writeFile('myfile2.txt', data, function(err){ if (err) { ... } // Handle error console.log('done') }); });
you can chain the operations together using then
from the returned promise:
let fs = require('fs'); let readFile = RSVP.denodeify(fs.readFile); let writeFile = RSVP.denodeify(fs.writeFile); readFile('myfile.txt').then(function(data){ return writeFile('myfile2.txt', data); }).then(function(){ console.log('done') }).catch(function(error){ // Handle error });
Defined in node_modules/rsvp/lib/rsvp/filter.js:8
RSVP.filter
is similar to JavaScript's native filter
method, except that it waits for all promises to become fulfilled before running the filterFn
on each item in given to promises
. RSVP.filter
returns a promise that will become fulfilled with the result of running filterFn
on the values the promises become fulfilled with.
For example:
let promise1 = RSVP.resolve(1); let promise2 = RSVP.resolve(2); let promise3 = RSVP.resolve(3); let promises = [promise1, promise2, promise3]; let filterFn = function(item){ return item > 1; }; RSVP.filter(promises, filterFn).then(function(result){ // result is [ 2, 3 ] });
If any of the promises
given to RSVP.filter
are rejected, the first promise that is rejected will be given as an argument to the returned promise's rejection handler. For example:
let promise1 = RSVP.resolve(1); let promise2 = RSVP.reject(new Error('2')); let promise3 = RSVP.reject(new Error('3')); let promises = [ promise1, promise2, promise3 ]; let filterFn = function(item){ return item > 1; }; RSVP.filter(promises, filterFn).then(function(array){ // Code here never runs because there are rejected promises! }, function(reason) { // reason.message === '2' });
RSVP.filter
will also wait for any promises returned from filterFn
. For instance, you may want to fetch a list of users then return a subset of those users based on some asynchronous operation:
let alice = { name: 'alice' }; let bob = { name: 'bob' }; let users = [ alice, bob ]; let promises = users.map(function(user){ return RSVP.resolve(user); }); let filterFn = function(user){ // Here, Alice has permissions to create a blog post, but Bob does not. return getPrivilegesForUser(user).then(function(privs){ return privs.can_create_blog_post === true; }); }; RSVP.filter(promises, filterFn).then(function(users){ // true, because the server told us only Alice can create a blog post. users.length === 1; // false, because Alice is the only user present in `users` users[0] === bob; });
Defined in node_modules/rsvp/lib/rsvp/hash.js:5
RSVP.hash
is similar to RSVP.all
, but takes an object instead of an array for its promises
argument.
Returns a promise that is fulfilled when all the given promises have been fulfilled, or rejected if any of them become rejected. The returned promise is fulfilled with a hash that has the same key names as the promises
object argument. If any of the values in the object are not promises, they will simply be copied over to the fulfilled object.
Example:
let promises = { myPromise: RSVP.resolve(1), yourPromise: RSVP.resolve(2), theirPromise: RSVP.resolve(3), notAPromise: 4 }; RSVP.hash(promises).then(function(hash){ // hash here is an object that looks like: // { // myPromise: 1, // yourPromise: 2, // theirPromise: 3, // notAPromise: 4 // } }); `
If any of the promises
given to RSVP.hash
are rejected, the first promise that is rejected will be given as the reason to the rejection handler.
Example:
let promises = { myPromise: RSVP.resolve(1), rejectedPromise: RSVP.reject(new Error('rejectedPromise')), anotherRejectedPromise: RSVP.reject(new Error('anotherRejectedPromise')), }; RSVP.hash(promises).then(function(hash){ // Code here never runs because there are rejected promises! }, function(reason) { // reason.message === 'rejectedPromise' });
An important note: RSVP.hash
is intended for plain JavaScript objects that are just a set of keys and values. RSVP.hash
will NOT preserve prototype chains.
Example:
function MyConstructor(){ this.example = RSVP.resolve('Example'); } MyConstructor.prototype = { protoProperty: RSVP.resolve('Proto Property') }; let myObject = new MyConstructor(); RSVP.hash(myObject).then(function(hash){ // protoProperty will not be present, instead you will just have an // object that looks like: // { // example: 'Example' // } // // hash.hasOwnProperty('protoProperty'); // false // 'undefined' === typeof hash.protoProperty });
Defined in node_modules/rsvp/lib/rsvp/hash-settled.js:14
RSVP.hashSettled
is similar to RSVP.allSettled
, but takes an object instead of an array for its promises
argument.
Unlike RSVP.all
or RSVP.hash
, which implement a fail-fast method, but like RSVP.allSettled
, hashSettled
waits until all the constituent promises have returned and then shows you all the results with their states and values/reasons. This is useful if you want to handle multiple promises' failure states together as a set.
Returns a promise that is fulfilled when all the given promises have been settled, or rejected if the passed parameters are invalid.
The returned promise is fulfilled with a hash that has the same key names as the promises
object argument. If any of the values in the object are not promises, they will be copied over to the fulfilled object and marked with state 'fulfilled'.
Example:
let promises = { myPromise: RSVP.Promise.resolve(1), yourPromise: RSVP.Promise.resolve(2), theirPromise: RSVP.Promise.resolve(3), notAPromise: 4 }; RSVP.hashSettled(promises).then(function(hash){ // hash here is an object that looks like: // { // myPromise: { state: 'fulfilled', value: 1 }, // yourPromise: { state: 'fulfilled', value: 2 }, // theirPromise: { state: 'fulfilled', value: 3 }, // notAPromise: { state: 'fulfilled', value: 4 } // } });
If any of the promises
given to RSVP.hash
are rejected, the state will be set to 'rejected' and the reason for rejection provided.
Example:
let promises = { myPromise: RSVP.Promise.resolve(1), rejectedPromise: RSVP.Promise.reject(new Error('rejection')), anotherRejectedPromise: RSVP.Promise.reject(new Error('more rejection')), }; RSVP.hashSettled(promises).then(function(hash){ // hash here is an object that looks like: // { // myPromise: { state: 'fulfilled', value: 1 }, // rejectedPromise: { state: 'rejected', reason: Error }, // anotherRejectedPromise: { state: 'rejected', reason: Error }, // } // Note that for rejectedPromise, reason.message == 'rejection', // and for anotherRejectedPromise, reason.message == 'more rejection'. });
An important note: RSVP.hashSettled
is intended for plain JavaScript objects that are just a set of keys and values. RSVP.hashSettled
will NOT preserve prototype chains.
Example:
function MyConstructor(){ this.example = RSVP.Promise.resolve('Example'); } MyConstructor.prototype = { protoProperty: RSVP.Promise.resolve('Proto Property') }; let myObject = new MyConstructor(); RSVP.hashSettled(myObject).then(function(hash){ // protoProperty will not be present, instead you will just have an // object that looks like: // { // example: { state: 'fulfilled', value: 'Example' } // } // // hash.hasOwnProperty('protoProperty'); // false // 'undefined' === typeof hash.protoProperty });
Defined in node_modules/rsvp/lib/rsvp/map.js:8
RSVP.map
is similar to JavaScript's native map
method, except that it waits for all promises to become fulfilled before running the mapFn
on each item in given to promises
. RSVP.map
returns a promise that will become fulfilled with the result of running mapFn
on the values the promises become fulfilled with.
For example:
let promise1 = RSVP.resolve(1); let promise2 = RSVP.resolve(2); let promise3 = RSVP.resolve(3); let promises = [ promise1, promise2, promise3 ]; let mapFn = function(item){ return item + 1; }; RSVP.map(promises, mapFn).then(function(result){ // result is [ 2, 3, 4 ] });
If any of the promises
given to RSVP.map
are rejected, the first promise that is rejected will be given as an argument to the returned promise's rejection handler. For example:
let promise1 = RSVP.resolve(1); let promise2 = RSVP.reject(new Error('2')); let promise3 = RSVP.reject(new Error('3')); let promises = [ promise1, promise2, promise3 ]; let mapFn = function(item){ return item + 1; }; RSVP.map(promises, mapFn).then(function(array){ // Code here never runs because there are rejected promises! }, function(reason) { // reason.message === '2' });
RSVP.map
will also wait if a promise is returned from mapFn
. For example, say you want to get all comments from a set of blog posts, but you need the blog posts first because they contain a url to those comments.
let mapFn = function(blogPost){ // getComments does some ajax and returns an RSVP.Promise that is fulfilled // with some comments data return getComments(blogPost.comments_url); }; // getBlogPosts does some ajax and returns an RSVP.Promise that is fulfilled // with some blog post data RSVP.map(getBlogPosts(), mapFn).then(function(comments){ // comments is the result of asking the server for the comments // of all blog posts returned from getBlogPosts() });
Defined in node_modules/rsvp/lib/rsvp/race.js:3
This is a convenient alias for RSVP.Promise.race
.
Defined in node_modules/rsvp/lib/rsvp/reject.js:3
This is a convenient alias for RSVP.Promise.reject
.
Defined in node_modules/rsvp/lib/rsvp/resolve.js:3
This is a convenient alias for RSVP.Promise.resolve
.
Defined in node_modules/rsvp/lib/rsvp/rethrow.js:1
RSVP.rethrow
will rethrow an error on the next turn of the JavaScript event loop in order to aid debugging.
Promises A+ specifies that any exceptions that occur with a promise must be caught by the promises implementation and bubbled to the last handler. For this reason, it is recommended that you always specify a second rejection handler function to then
. However, RSVP.rethrow
will throw the exception outside of the promise, so it bubbles up to your console if in the browser, or domain/cause uncaught exception in Node. rethrow
will also throw the error again so the error can be handled by the promise per the spec.
function throws(){ throw new Error('Whoops!'); } let promise = new RSVP.Promise(function(resolve, reject){ throws(); }); promise.catch(RSVP.rethrow).then(function(){ // Code here doesn't run because the promise became rejected due to an // error! }, function (err){ // handle the error here });
The 'Whoops' error will be thrown on the next turn of the event loop and you can watch for it in your console. You can also handle it using a rejection handler given to .then
or .catch
on the returned promise.
© 2017 Yehuda Katz, Tom Dale and Ember.js contributors
Licensed under the MIT License.
https://emberjs.com/api/ember/2.15/classes/RSVP/methods