TypeScript 2.0

• Null- and undefined-aware types
• Control flow based type analysis
• Tagged union types
• The never type
• Read-only properties and index signatures
• Specifying the type of this for functions
• Glob support in tsconfig.json
• Module resolution enhancements: BaseUrl, Path mapping, rootDirs and tracing
• Shorthand ambient module declarations
• Wildcard character in module names
• Support for UMD module definitions
• Optional class properties
• Private and Protected Constructors
• Abstract properties and accessors
• Implicit index signatures
• Including built-in type declarations with –lib
• Flag unused declarations with –noUnusedParameters and –noUnusedLocals
• Module identifiers allow for .js extension
• Support ‘target : es5’ with ‘module: es6’
• Trailing commas in function parameter and argument lists
• New –skipLibCheck
• Allow duplicate identifiers across declarations
• New –declarationDir