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Usage of promise

"Promise" is a programming concept used to handle asynchronous operations. It can be used to represent the final result of an asynchronous operation. Promise objects have three states: pending (in progress), fulfilled (successful) and rejected (failed). The usage of Promise mainly includes constructors, instance methods (then, catch, finally) and state transitions.

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Usage of promise

How to use promise

Oct 12, 2023 pm 05:08 PM

promise

What is the use of promise in es6

In es6, promise is used to create promise objects and perform asynchronous operations. The syntax is "const promise = new Promise((resolve,reject)=>{...})"; it holds the status of asynchronous operations and is used to represent Different results for asynchronous operations.

Mar 30, 2022 pm 04:23 PM

es6

es6 promise has several states

There are three states: 1. pending, which means it is in progress and this state will be initialized; 2. fulfilled, which means it has been successful; 3. rejected, which means it has failed and will trigger the subsequent catch callback function. After the promise's status is changed, it will solidify and will not change again. This result will always be maintained.

May 19, 2022 pm 04:30 PM

es6 promise

Is promise based on es6?

Yes. Promise is a new reference type in ECMAScript 6, which represents the final completion or failure of an asynchronous operation. Promise solves the problem of overly complex logic writing in asynchronous programming calling code. When the network request is very complex, callback hell will occur. In this way, if these codes are written together, they will look very complicated and not conducive to reading. If you use Promises will make the code look more beautiful and elegant.

Nov 03, 2022 pm 07:20 PM

es6 promise

What are the states of promise objects in es6

Status: 1. Pending status, which is initialized and there is no result in the process; 2. Fulfilled success status, the resolved status will trigger the subsequent then callback function; 3. Rejected failure status, the rejected status will trigger the subsequent then callback function. catch callback function.

Mar 31, 2022 pm 06:38 PM

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One article will help you master Promise easily

In front-end js learning, the most uncomfortable thing for everyone is the problem of asynchronousness. To solve problems such as asynchronous and callback hell, you must learn promises. For most front-end programmers, promises are simply a nightmare. This article starts from the easy-to-understand Angle is used as the entry point to help everyone easily master promises.

Feb 10, 2023 pm 07:49 PM

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