What are the best statically typed extensions of JavaScript?

4

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13

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Jun 17, 2018

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Here’s the Deal

4 Options Considered

4 Options Considered	Price	Price	Site
-- TypeScript	-	Free, Open source	http://www.typescriptlang.org/
-- Kotlin	-	Free, Open Source	http://kotlinlang.org
-- Scala.js	-	Free	https://www.scala-js.org/
-- Flow	-	–	–

TypeScript

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Top Pro

Adds support for object-oriented programming

Typescript enables familiar object-oriented programming patterns: classes, inheritance, public/private methods and properties, et cetera. See More

Top Con

Type inference coverage is incomplete

The default type when declaring and using a variable is any. For example, the following should break but does not: function add(a:number) { return a + 1 } function addAB(a, b) {return add(a) + b} addAB("this should break but doesn't :(", 100) In order to avoid this, you have to declare type signatures for every variable or parameter or set the flag --noImplicityAny when running the compiler. See More

Top Pro

Strict superset of Javascript

Every existing Javascript program is already a valid TypeScript program giving it the best support for existing libraries, which is particularly useful if you need to integrate with an existing Javascript code base. See More

Top Con

Unversioned community type definitions

It can be difficult to find type annotations for older versions of different libraries because community type definitions are not versioned. See More

Top Pro

Polyfill for ES6 fat-arrow syntax

Typescript implements the fat arrow syntax, which always maintains the current context for this and is a shorter/more convenient syntax than traditional function definition. See More

Top Pro

Built and Supported by Microsoft

Being built by Microsoft, TypeScript is much more likely than most other similar open-source projects to receive continued long-term support, good documentation, and a steady stream of development. See More

Top Pro

First party Visual Studio support

As a Microsoft developed project, it has first party Visual Studio support that's on par with its C# support with features like syntax sensitive statement completion . See More

Top Pro

Optional static typing

Typescript has optional static typing with support for interfaces and generics, and intelligent type inference. It makes refactoring large codebases a breeze, and provides many more safeguards for creating stable code. See More

Top Pro

Has a repository of high quality TypeScript type definitions for popular libraries

There are many ready to use and high quality TypeScript definitions for popular libraries including jquery, angular, bootstrap, d3, lodash and many-many more. See More

Top Pro

Great support for React, integrated typed JSX parsing

Strongly typed react components, so UI "templating" automatically gains type safety. See More

Specs

Price:Free, Open source

Site:http://www.typescriptlang.org/

Current stable version:2.3

Kotlin

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May be hard for programmers already used to imperative style to learn functional programming from Kotlin

Since Kotlin does not enforce any particular paradigms and is not purely functional, it can be pretty easy to fall back to imperative programming habits if a programmer comes from an imperative background. See More

Top Pro

Is built to solve industrial problems

Kotlin has been designed and built by developers who have an industrial background and not an academic one. As such, it tries to solve issues mostly found in industrial settings. For example, the Kotlin type system helps developers avoid null pointer exceptions. Reasearch languages usually do not have null at all, but APIs and large codebases usually need null. See More

Top Pro

Does not impose a particular philosophy of programming

It's not overly OOP like Java and it does not enforce strict functional paradigms either. See More

Top Pro

Officially supported for Android development

Starting with version 3.0 of Android Studio, Kotlin support will be built-in. This means that it's now easier than ever to use Kotlin for existing Android projects or even start writing Android apps only with Kotlin from scratch. This also means that Kotlin and Kotlin plugins for Android Studio will be fully supported in the future and their likelihood of being abandoned is quite small since Google is fully embracing the language for their Android ecosystem (alongside Java and C++). See More

Top Pro

No runtime overhead

The standard library is relatively small and tight. It mostly consists of focused extensions of the Java standard library and as such adds no additional runtime overhead to existing Java projects. See More

Top Pro

Easy adoption for existing Java programmers

Kotlin runs on the JVM and Java interoperability has been one of the main objectives since the language was born. It runs everywhere Java does; web servers, mobile devices (Android), and desktop applications. It also works with all the major tools in the Java ecosystem like Eclipse, IntelliJ, Maven, Ant, Gradle, Spring Boot, etc. All of this makes adoption extremely easy even for existing Java projects. On top of this there's also ensured Type safety and less boilerplate code needed. See More

Top Pro

Great tooling support

Since Kotlin is made by Jetbrains (the developers of IntelliJ IDEA) so it stands to reason that the IntelliJ support for Kotlin is also great. Besides that, Kotlin also works well with existing Java tools such as Eclipse, Maven, Gradle, Android Studio, etc. See More

Specs

Price:Free, Open Source

Site:http://kotlinlang.org

Current stable version:1.2

Scala.js

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Macros

Because Scala.js is a plugin to the Scala compiler, the whole power of the Scala language is available at compile-time. Which includes macros. Very expressive things can be done, in a type-safe way, which are difficult or impossible in other languages. See More

Top Pro

Extensive standard libraries

Scala.js implements most of the Scala standard library and many parts of the Java one. Among others, it supports Scala's rich collection library. See More

Top Pro

Type inference

Scala offers type inference, which, while giving the same safety as Java's type system, allows programmers to focus on the code itself, rather than on updating type annotations. See More

Specs

Site:https://www.scala-js.org/

Current stable version:0.6.18

Flow

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Checks to see if you check for Nulls

Because getting those exceptions is just not fun and very pervasive. See More

Top Con

Weak base type definitions even for popular JavaScript libraries

For example, there are definitions for Gulp, React. See More

Top Pro

Versioned type definitions

Top Pro

There is support in many code editors via the extension

For example, there is good support through the extension in Visual Studio Code, which is a good editor for TypeScript, which is a competitor to Flow. See More

Top Pro

Babel extension for strip of type annotations

Thanks to the Babel extension for the output, there is minimally modified code that is understandable to the author. See More

Top Pro

Statical analysing of JavaScript code

Statical analysing of JavaScript code without pre-making any changes to it. But supported annotation types by extending the syntax of the language. See More

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Extensive standard libraries

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Recommended 2 years ago

Strict superset of Javascript

Optional static typing

Polyfill for ES6 fat-arrow syntax

Built and Supported by Microsoft

Has a repository of high quality TypeScript type definitions for popular libraries

First party Visual Studio support

Adds support for object-oriented programming

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