https://github.com/jeantimex/how-to-implement-promise
How to implement a Promise that is Promises/A+ compliant using vanilla JavaScript.
https://github.com/jeantimex/how-to-implement-promise
promise promise-aplus vanilla-js
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How to implement a Promise that is Promises/A+ compliant using vanilla JavaScript.
- Host: GitHub
- URL: https://github.com/jeantimex/how-to-implement-promise
- Owner: jeantimex
- License: mit
- Created: 2018-08-21T18:41:17.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2018-08-27T06:06:15.000Z (over 6 years ago)
- Last Synced: 2024-10-30T02:28:24.605Z (6 months ago)
- Topics: promise, promise-aplus, vanilla-js
- Language: JavaScript
- Homepage:
- Size: 53.7 KB
- Stars: 5
- Watchers: 3
- Forks: 0
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# How to Implement Promise
[](https://travis-ci.org/jeantimex/how-to-implement-promise)
Implement a Promise that is Promises/A+ compliant using vanilla JavaScript.
## Example Usage
```javascript
const Promise = require("./promise");
```
### Basic
```javascript
Promise.resolve(233)
.then()
.then(function(value) {
console.log(value);
});
```
### setTimeout
```javascript
function delay(ms) {
return new Promise(function(resolve) {
setTimeout(resolve, ms);
});
}
(async function print() {
console.time("setTimeout");
await delay(1000);
console.timeEnd("setTimeout");
})();
```
### Promise.all
```javascript
const promise1 = Promise.resolve(3);
const promise2 = 42;
const promise3 = new Promise(function(resolve, reject) {
setTimeout(resolve, 100, "foo");
});
const promise4 = new Promise(function(resolve, reject) {
setTimeout(resolve, 200, "bar");
});
Promise.all([promise1, promise2, promise3, promise4]).then(function(values) {
console.log(values);
});
```
### Promise.race
```javascript
const promise1 = new Promise(function(resolve, reject) {
setTimeout(resolve, 500, "one");
});
const promise2 = new Promise(function(resolve, reject) {
setTimeout(resolve, 100, "two");
});
Promise.race([promise1, promise2]).then(function(value) {
console.log(value);
});
```
## Test with Promise/A+ specs
```
npm run test
```
Note: The Promises/A+ compliance test suite can be found [here](https://github.com/promises-aplus/promises-tests).
## References
1. [Promise/A+ Specs](https://promisesaplus.com/)
2. [MDN - Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise)
3. [Implementing Promise](https://www.promisejs.org/implementing/)
4. [Implementing promises from scratch](https://www.mauriciopoppe.com/notes/computer-science/computation/promises/)
5. [Promises, Next-Ticks and Immediates](https://jsblog.insiderattack.net/promises-next-ticks-and-immediates-nodejs-event-loop-part-3-9226cbe7a6aa)
6. [深入理解 Promise (中)](http://coderlt.coding.me/2016/12/04/promise-in-depth-an-introduction-2/)
7. [解读Promise内部实现原理](https://juejin.im/post/5a30193051882503dc53af3c)