One of the big issues with using either callbacks or Promises is that the code becomes much more complex that it would, if you were using a synchronous programming language. This is where async and await comes in. The keywords are borrowed from C# and .NET and is without doubt one of my favorite features of using C#.
\nYou need to prefix your function with the “async” keyword before you can use the await keyword. And every async method will return a promise.
\nThis means that you could make a promise by making a async method and use return and throw instead of a regular promise with resolve and reject.
\nSo, you\u2019re inside a async method and want to fetch some data from a method that returns a promise; either a promise or another async method. You could either use .then() like before or you could just do something like this:<\/p>\n
let data = await method()<\/pre>\nLook at the full example below:<\/p>\n
async function a(){\r\n let data = await b()\r\n data = await Promise.all(data.map(async d => d*2))\r\n return data\r\n}\r\nasync function b(){\r\n return [1,2,3]\r\n}\r\na().then(r => console.log(r))<\/pre>\nI think that async \/ await in general makes code less complex, because you can hide most of the callback \/ promise stuff behind the await keyword, and treat it more like a regular program in for example Python or Ruby. But remember that every method that uses await, need to be async; this means that you need to do this “hack”:
await Promise.all(data.map(async d => d*2))<\/code> hack if you need to do await inside a map. Because the map code will return an array of promises. Like I said, all async methods returns a promise. Then, you can resolve them using promise all, and if you prefix it with await, it will give you the result of all of them in an array as result.
\nAgain, Promises and Async methods are two sides of the same coin. I personally look at Promises as the technology behind it all, and mostly use async await to make and deal with them.<\/p>\n","protected":false},"excerpt":{"rendered":"One of the big issues with using either callbacks or Promises is that the code becomes much more complex that it would, if you were using a synchronous programming language.…<\/p>\n","protected":false},"author":7,"featured_media":3127,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[2],"tags":[82,83,84,85],"powerkit_post_featured":[],"class_list":{"0":"post-3169","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-javascript","8":"tag-async","9":"tag-await","10":"tag-programming-asynchronously","11":"tag-promises"},"jetpack_featured_media_url":"https:\/\/i0.wp.com\/code4developers.com\/wp-content\/uploads\/2017\/10\/javascript.jpg?fit=750%2C422&ssl=1","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p8NAi4-P7","jetpack-related-posts":[{"id":3174,"url":"https:\/\/code4developers.com\/for-of-loop\/","url_meta":{"origin":3169,"position":0},"title":"For-of Loop","author":"Arif Khoja","date":"December 25, 2017","format":false,"excerpt":"For of loop is one of a few recent additions to the for loop in JavaScript. It makes it possible to do what is basically a foreach in most other programming languages, like for example C#. for(var item of array){} is more or less the same as foreach(var item in\u2026","rel":"","context":"In "JavaScript"","block_context":{"text":"JavaScript","link":"https:\/\/code4developers.com\/category\/javascript\/"},"img":{"alt_text":"javascript","src":"https:\/\/i0.wp.com\/code4developers.com\/wp-content\/uploads\/2017\/10\/javascript.jpg?fit=750%2C422&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/code4developers.com\/wp-content\/uploads\/2017\/10\/javascript.jpg?fit=750%2C422&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/code4developers.com\/wp-content\/uploads\/2017\/10\/javascript.jpg?fit=750%2C422&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/code4developers.com\/wp-content\/uploads\/2017\/10\/javascript.jpg?fit=750%2C422&ssl=1&resize=700%2C400 2x"},"classes":[]},{"id":3818,"url":"https:\/\/code4developers.com\/slicepipe-jsonpipe-asyncpipe\/","url_meta":{"origin":3169,"position":1},"title":"Pipes in Angular Part \u2013 4 : SlicePipe, JSONPipe, AsyncPipe","author":"Yatendrasinh Joddha","date":"August 19, 2018","format":false,"excerpt":"Here is the fourth part of angular pipe series in this part we will discuss about SlicePipe, JSONPipe, and AsyncPipe. 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So far, four proposals have been finalized for inclusion in the ECMAScript 2018 specification, said Zibi Braniecki,\u2026","rel":"","context":"In "JavaScript"","block_context":{"text":"JavaScript","link":"https:\/\/code4developers.com\/category\/javascript\/"},"img":{"alt_text":"ecma script","src":"https:\/\/i0.wp.com\/code4developers.com\/wp-content\/uploads\/2017\/10\/ecma.png?fit=400%2C277&ssl=1&resize=350%2C200","width":350,"height":200},"classes":[]},{"id":3171,"url":"https:\/\/code4developers.com\/programming-asynchronously-promises\/","url_meta":{"origin":3169,"position":3},"title":"Programming asynchronously: Promises","author":"Arif Khoja","date":"December 20, 2017","format":false,"excerpt":"Promises are in many ways the logical next step from callback. A promise is just a special object that promise to either resolve, or throw an exception. Promises are easy to use, and easy to make. 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