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Type script = javascript (alomst) done right
This document introduces TypeScript as a superset of JavaScript that adds optional type checking, classes, interfaces and other features. It was developed by Anders Hejlsberg at Microsoft to address issues with JavaScript as applications grow larger and more complex. Key features discussed include type annotations, type inference, modules, classes, and interfaces. The document argues that TypeScript can help with large JavaScript projects while allowing existing JavaScript code and skills to still be used.
Type script = javascript (alomst) done right
- 1. TypeScript = JavaScript(almost) done right Maurice de Beijer
- 2. Who am I Maurice de Beijer The Problem Solver Microsoft MVP since 2005 DevelopMentor instructor Twitter: @mauricedb Blog: http://msmvps.com/blogs/theproblemsolver/ Web: http://www.HTML5Support.nl E-mail: Maurice.de.Beijer@gmail.com
- 3. Agenda What isTypeScript? Why do we need TypeScript? What is wrong with JavaScript? TypeScript features Type annotations Type inference Modules Classes
- 4. What is TypeScript? An open source programming language developed at Microsoft By Anders Hejlsberg, lead architect of C# A super set of JavaScript All JavaScript is valid TypeScript Adds optional type checking, classes, interfaces and more Compiles to “normal” JavaScript Either ECMAScript 5 or ECMAScipt 3
- 5. Why do weneed TypeScript? JavaScript was designed for small scripts These days JavaScript applications get bigger and more complex Gmail is reported to have 443,000 lines of JavaScript in 2010 This trend will continue Single Page Applications in the browser Node.js on the server
- 6. What is wrongwith JavaScript?
- 7. Douglas Crockford onTypeScript Microsoft's TypeScript may be the best of the many JavaScript front ends. It seems to generate the most attractive code. And I think it should take pressure off of the ECMAScript Standard for new features like type declarations and classes. Anders has shown that these can be provided nicely by a preprocessor, so there is no need to change the underlying language. I think that JavaScript's loose typing is one of its best features and that type checking is way overrated. TypeScript adds sweetness, but at a price. It is not a price I am willing to pay.
- 8. Things TypeScript addsto JavaScript Type annotations Type inference Modules Classes Interfaces Based on the ECMAScript 6 proposed standard
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- 15. TypeScript type definitions The DOM and standard JavaScript types are provided
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- 20. Interfaces & functionoverloading
- 21. Interfaces & typedefinitions
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- 29. TypeScript is stillJavaScript Not all JavaScript problems are solved by TypeScript Some older browsers support ECMAScript 3 (December 1999) Some older browsers have non standard DOM/CSS implementations jQuery remains an extremely useful library
- 30. Conclusion TypeScript isnot perfect But it helps a lot You are not forced to use a new language Leverage existing JavaScript skills en libraries Consider it for your next “large“ JavaScript project After all the risk is small