Class Decorators A Class Decorator is declared just before a class declaration. The class decorator is applied to the constructor of

Global Functions Documentation You can call the function greet with a string

Optional and Default Parameters In TypeScript, every parameter is assumed to be required by the function. This doesn’t mean that it can’t be

Number As in JavaScript, all numbers in TypeScript are floating point values. These floating point numbers get the type number

Type assertions Sometimes you’ll end up in a situation where you’ll know more about a value than TypeScript does. Usually this will happen when

Multi-file namespaces Here, we’ll split our Validation namespace across many files. Even though the files are separate, they can

Ambient Namespaces The popular library D3 defines its functionality in a global object called d3. Because this library is loaded

export = and import = require() Both CommonJS and AMD generally have the concept of an exports object

Aliases Another way that you can simplify working with of namespaces is to use import q = x.y.z to create shorter names for commonly-used

Add TypeScript The next step is to add a folder for TypeScript.