However, this keyword often makes variables to have function scope with the possibility of being hoisted to the top. Previously, the var keyword was used to define all types of variables, even if they are constants. Others said we don’t need promises and can just use async, generators, callbacks, etc.ES6 introduced let and const keywords which allow you to declare reassignable variables and constants respectively. q, bluebird, deferred.js, vow, avow, jquery deferred to name just a few. There were a lot of promise implementations with slightly different syntax. Promises have been a controversial topic. Remember we had to do these statements to define default parameters: var link = function (height, color, url) `) // implicit return 2015: ES6/ECMAScript2015 comes out it has mostly syntactic sugar, because people weren’t able to agree on anything more ground breaking (ES7?)Įnough with history, let’s get to the business of coding.2009: ES5 comes out (this is what most of us use now) with forEach, Object.keys, Object.create (specially for Douglas Crockford), and standard JSON.AJAX, gains popularity in app such as Outlook Web Access (2000) and Oddpost (2002), Gmail (2004) and Google Maps (2005). 1999: ES3 comes out and IE5 is all the rage.1997: ECMAScript standard is established.It is in no way was intended to diminish usefulness of other ES6 features, which didn’t make it to the list simply because I had to limit the number to 10.įirst, a bit of history because those who don’t know the history can’t make it. Here’s the list of the top 10 best ES6 features for a busy software engineer (in no particular order):ĭisclaimer: the list if highly biased and subjective. If you’re a busy JavaScript software engineer (and who is not?), then proceed reading to learn the best 10 features of the new generation of the most popular programming language-JavaScript. If you don’t know what is ES6, it’s a new JavaScript implementation. This essay will give you a quick introduction to ES6. Half of the talks I went to were about ES6 or, as it’s now called officially, ECMAScript2015.

I recently went to HTML5 Dev conference in San Francisco.

Es6 features