The variables declared using let are block-scoped. To learn more about the difference between let and var, visit JavaScript let vs var. Previously, variables were declared using the var keyword. JavaScript let is used to declare variables. This tutorial provides a brief summary of commonly used features of ES6 so that you can start quickly in ES6.
ECMAScript provides the specification on how JavaScript programming language should work. X.JavaScript ES6 (also known as ECMAScript 2015 or ECMAScript 6) is the newer version of JavaScript that was introduced in 2015.ĮCMAScript is the standard that JavaScript programming language uses. Here is some ES5 code that will calculate the square of every value in an array and log the value to the console var x = TC39 should embrace, clean-up, and extend rather than re-invent or compete with de-facto and nearby de-jure standards. Hard to beat C# and CoffeeScript here (we want the unparenthesized single-parameter form as in C#). Check out the wiki regarding arrow functions: If you’re a C# developer who has ever used lambda expressions, the syntax will feel very familiar. The most common approach is probably the special constructor function like this function Car( make ) There are several options to approximate classes in ES5. In this post I’ll cover classes, Arrow Functions, Modules, Block Scoping, and Promises. There are quite a few new features in ES6, many still in draft form. ES6 will tackle many of the core language shortcomings addressed in TypeScript and CoffeeScript. Both TypeScript and CoffeeScript provide syntactic sugar on top of ES5 and then are transcompiled into ES5 compliant JavaScript. NET world (and here at Wintellect) and CoffeeScript is kind of a big deal™ in the Ruby community. As such, several workarounds have emerged.
Folks coming from the backend development space find ES5 lacks some pretty basic language features. The current version of EcmaScript supported in modern browsers is ES5 (with some ES6 support). A new version of EcmaScript will have a broad impact on web development. Every browser has a JavaScript interpreter, JavaScript on the server is becoming ever more popular, and now it’s possible to use JavaScript for desktop ( Chrome Apps), nativish mobile ( PhoneGap) and native Windows 8 apps.
Naming aside, JavaScript is one of the most important languages in existence today. Brendan Eich, the original developer of JavaScript, once wrote that the name EcmaScript sounds like a skin disease. If you think EcmaScript is a terrible name, you’re not alone. EcmaScript is the standardized scripting language that JavaScript (and some other languages, like ActionScript) implement.
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