constmyFirstPromise=newPromise((resolve,reject)=>{// We call resolve(...) when what we were doing asynchronously was successful, and reject(...) when it failed.// In this example, we use setTimeout(...) to simulate async code.// In reality, you will probably be using something like...
In the example, we wait for all promises to finish and in the end, we calculate the sum of returned values. $ node all.js finished 600 JS multiple requests with axios In the next example, we use the axois library to execute multiple get requests. Axios is a promise-based HTTP client ...
if ("Promise" in window) { let btn = document.getElementById("make-promise"); btn.addEventListener("click",testPromise); } else { log = document.getElementById('log'); log.textContent = "Live example not available as your browser doesn't support the Promise interface."; } Copy to Cli...
复制 constpromise1=fetch('https://api.example.com/data1');constpromise2=fetch('https://api.example.com/data2');constpromise3=fetch('https://api.example.com/data3');Promise.all([promise1,promise2,promise3]).then(values=>{console.log('所有数据已获取:',values);}).catch(error=>{consol...
Promise最早出现在 1988 年,由Barbara Liskov、Liuba Shrira首创(论文:Promises: Linguistic Support for Efficient Asynchronous Procedure Calls in Distributed Systems)。并且在语言MultiLisp和Concurrent Prolog中已经有了类似的实现。 JavaScript 中,Promise的流行是得益于jQuery的方法jQuery.Deferred(),其他也有一些更精简...
example2 in Nodejs //db.jsfindDemandManger=(data)=>{// need change to promisereturnnewPromise((resolve,reject)=>{//asyncmaggie.view('all','new',{include_docs:true},function(err,body){letuserid='';if(!err){constBreakException={};try{body.rows.forEach(function(doc){if(doc.doc.Domai...
首先,创建一个名为promise-demo的新项目文件夹,并在其中创建一个名为createPromise.js的文件。 mkdir promise-democdpromise-demo touch createPromise.js 步骤2:编写代码 在createPromise.js文件中,我们将编写代码来创建一个 Promise,并使用resolve和reject。
$ node promise.all.js error = promise error promisesOK values = [ 3, 42, 'foo' ] OK = Promise { undefined } Error = Promise { undefined } */ 原理分析 Promise.resolve, Promise.reject // Promise,不许需要用 Promise 包裹,但为了对齐也使用 Promise 包裹promise1 =Promise.resolve(3);// Pr...
function timeout(timeoutInMs, promise) { return Promise.race([ promise, resolveAfter(timeoutInMs, Promise.reject(new Error('Operation timed out'))), ]); } timeout() 返回一个Promise,该 Promise 的状态取决于传入 promise 状态。 其中timeout 函数中的 resolveAfter(timeoutInMs, Promise.reject...
Even in the case of non-remote objects, these methods can be used as shorthand for particularly-simple fulfillment handlers. For example, you can replacereturn Q.fcall(function () { return [{ foo: "bar" }, { foo: "baz" }]; }) .then(function (value) { return value[0].foo; });...