Disclaimer

Turbo Pascal, C#, TypeScript

Thank you!

Rising popularity

Overall magnitude

JavaScript in "real world"

Superset in theory

Superset in practice

TypeScript as a cure ...

JS problems

• class vs prototypical inheritance
• object - oriented vs functional programming
• conversion - casting vs coercion
• variables  - block scope vs function scope
• functions as variable - "first category citizen"

Main features

• added compilation - types checks, ...
• some of ES-next features - async/await
• classes and interfaces,
• editors autocomplete - really missed that,
• strict rules via tslint - even on convention or editor level

Lessons learned

Good

• API is clear and readable
• compilation time is ok,
• features variety is stunning,
• tslint is really powerful and useful,

Bad

• JS is the vast ecosystem - not everybody is considering TS,
• test, debug, build and package management is still nightmare - against all community effort,
• code autocomplete comes with the price