Today, the TypeScript team released TypeScript 1.5 as part of the .NET 4.6 announcement. Back in January, the team finished TypeScript 1.4; now, an alpha and a beta release later, TypeScript 1.5 is here and ships with a lot of goodness.
The most notable improvement that TypeScript 1.5 offers is its extensive support for ECMAScript 2015 (aka ES6). While version 1.4 implemented only a few of the new language features, TypeScript 1.5 now implements all but a few. This is a huge step indeed: We've gone from almost no support to almost full support.
Note that while TypeScript transpiles new ECMAScript 2015 language features to a downleveled version for ES3 and ES5, it doesn't polyfill any new functionality that's been added to the standard library (such as the new collection types
For an overview of which ECMAScript 2015 features have already been implemented and which ship with the next version, take a look at the official TypeScript roadmap. The TypeScript team also maintains a document highlighting what's new in TypeScript. Finally, the ECMAScript 6 compatibility table lists which transpilers currently support which new features.
The last weeks, I spent a lot of time writing code in TypeScript. I wanted to use all the good ECMAScript 2015 languages features like modules, arrow functions, and