Type definition file

• Adaptor between ts code and js libraries
• Some libraries include automatically. E.g. axios, express
• To install: @types/{library-name}. E.g. @types/faker
• Ctrl+Click on the library brings to the type definition file (index.d.ts)

Global variable in the project

• Need also a type definition file
• E.g. google maps script on HTML
• Install: @types/googlemaps
• Typing 'google' now shows the available methods

Type definition files

• @types/node
• @types/googlemaps
• @types/faker
• @types/express
• @types/cookie-session
• @types/mongoose
• @types/cookie-session
• axios (built in)
• HTML (built in into Node.js). E.g. HTMLElement
• ts-express-decorators (decorator for express)