What is a Promise on the front end?

The role of turning asynchronous to synchronous.

Recently, when you were looking for a front-end job, and then during the interview, people asked you to go quickly and directly based on what you have learned at that time.

ES2015 (i.e., ECMAScript 6, ES6) was released. Promises are listed as official specifications and become one of the most important features in ES6.

To put it simply, the then method is to separate the original writing method, and execute the ** function in the form of a chain call after the asynchronous operation is executed.

The advantage of promises is this chain call. We can continue to write the promise object in the then method and return it, and then continue to call then to do the ** operation.

v.Promise; Promise; Promise; Guarantee; Make it very likely; Foreshadow.

n.Promise; Promise; Promise; signs of success; auspicious signs; Sign.

1. Pronunciation: English [ pr m s], American [ prɑ m s].

2. Usage: promise is used as a transitive verb, followed by a noun, pronoun, verb infinitive or that clause as an object.

It can also be followed by a noun, a verb infinitive, and that clause as a direct object, and its indirect object can be converted into the object of the preposition to.

3. Collocation phrases:

promise technology ; Promise Technology ; Promise Information ; Promise Information.

Greatest promise ; Bright future; A lot of hope.

Promise Yourself.

Chinese means promise, promise; Wish.

promise

English [ pr m s] American [ prɑ m s].

n.Promise, promise; Wish.

vt.Promise, promise; Give people a sense of....of hope or hope.

vi.Promise; There is hope, there is a future.

Past tense promisedPast participle promised present participle promising plural promises third person singular promises ].

Fixed collocation: promise technology; Promise Technology ; Promise Information ; Promise Consulting.

promise n ; Promise; Future; Promise;

Promise Yourself.

Greatest promise ; Bright future; A lot of hope.

promise [ pr m s].

Beauty [prɑ:m s].

vt.Promise, promise; Give people a sense of....of hope or hope.

vi.Promise; There is hope, there is a future.

n.Promise; Hope, hope; Something promised;

network] conventions; Promise; Promise;

They also promise to treat the tigers humanely

We promise to treat these mountain kings humanely.

Other] Third person singular: promises Plural: promises present participle: promising Past tense: promised Past participle: promised

Good question, one of the core of the promise mechanism: the then method returns another promise2, the content of which is determined by the return value of the ** method; Promise3 can be returned, so that the content of the outer promise2 becomes the content of promise3, that is, if you want to use the promise to recursively, you only need to return the recursive promise in then**.

In the implementation of the then method, a new promise is indeed returned, and the double you say is actually the first argument of then onfulfilled. = function (onfulfilled, onrejected) {var self = this; return new promise(function (resolve, reject) {return

If you have strong self-control and a strong sense of autonomy, you will definitely be able to devote yourself to self-study. Of course, in addition to learning theoretical knowledge to do some simple applications, if you are a software major, you can participate in HTML5 training, training 18 weeks should have some experience, at this time to go out to find a job from the internship can start.

Can work: can write basic dynamics in JS, bind events, and manipulate the DOM native or in JQ.

Barely passable: Proficiency in both of the above two items and the ability to write more complex interactions in JS. You can find a front-end job and get to work here.

Qualified: Know how to implement JS inheritance, be able to say a new process, use closures wisely, use promises, AMD cmd modularization, use underscore, and write regulars. There will be two or three of them.

At this point, you should be able to find a front-end job for an Internet company that is short of people and is not bad.

Okay: can handwrite JS prototype chain inheritance, know the implementation mechanism of a promise, can write most of the functions in underscore, handwrite delegate, and can basically understand what it is doing by finding a random library. I think I'll be able to rush the bat at this point.

Yes: There is research on the optimization of page performance, MVC frameworks can analyze the advantages and disadvantages, and there is research on packaged publishing tools. It can be regarded as a reliable front-end on this one.

Talent: Write the required packaging and release modular tools according to business needs, have the ability to write their own frameworks, have their own insights into the development process and methods, do not rely on class libraries, write a module whatever the project needs, and have built countless wheels. You can pick and choose from this domestic front-end job.

HTML belongs to the most basic thing in the front-end.,It's just a simple HTML web page layout.,It's probably not easy to find.,A lot of things at the front-end need to be processed interactively.,You need to use JS.,So you have to learn JS.

There are a few small phrases.

promise oneself , promise yourself.

Keep promise.

show promise has the hope of success.

make a promise allowed; Promise;

Greatest promise; Promising on a promise (message, gift, etc.) promise to do , promise to pay for the promise.

solemn promise Promise well has a good outlook; Very promising show greatest promise great promise, great hope break a promise to break a promise.

Hope it helps

As a practitioner engaged in the child-related industry, I would like to tell you seriously, if you are really interested in this industry, it is important to have a solid foundation of basic knowledge during college, and you must develop well in the future, which is necessary in order to go better and keep up. Now those training institutions are to teach you what is commonly used in the work, you will learn this sooner or later, if you really want to go higher and better, you must finish it well, and large enterprises are also willing to cultivate such people, rather than coming out to be the best porter, to be a thinking person. As for the fear of less experience, why don't you check the information on the Internet yourself, there are so many online resources, such as the backing network, the first-class tutor is very helpful, but why not try to do something yourself?

There is no need to go to a training institution, and there is also an advantage to going to a training institution, which is to get to know people, which may be the case.

Basically, there is no requirement, but the front-end needs to be tiled, and if you want to use a large ps** psd file for the process, you need to configure a higher computer, otherwise it will be stuck.

promise

vt.Promise, promise; Give people a sense of....of hope or hope.

vi.Promise; There is hope, there is a future.

n.Promise; Hope, hope; Something promised;

Plural: promisesThird person singular: promisesPast tense: promisedPast participle: promisedPresent participle: promising

Verb: promise Fixed usage: promise to do sth

Noun: commitment.

vt.Promise, promise; Give people a sense of....of hope or hope.

vi.Promise; There is hope, there is a future.

n.Promise; Hope, hope; Something promised;

Plural: promisesThird person singular: promisesPast tense: promisedPast participle: promisedPresent participle: promising

Confusing word: promisepromise

In English, promise can be used as a verb or as a noun, and when it is a noun, it means promise, hope. When you do a verb it means, right. Make a commitment.

Promise, promise; Give people a sense of....of hope or hope.