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TypeScript #

• You can specify the type of the arguments being passed to a function with func<type>(var), e.g. helloWorld<string>("test")
  • The angle brackets should only be used when using generic types
  • When you call helloWorld<string>("test") the helloWorld function accepts a generic type and you are setting the generic type to be a string
  • You can have multiple types within the angle brackets for the multiple arguments
  • This is often done by type inference with helloWorld("test")
• For generic functions, you can use any, but this loses the information of the type that is passed in. The generic Type can be used to specify the type of the variable and the return type (e.g. making sure they are both of generic type Type)
• Arrays can either be declared Array<string> or string[]
• Using | between types is an or
• declare function ... just specifies the types of a function, not its implementation
• *.d.ts files are used to provide type information for modules written in pure js
  • You nam *.d.ts the same as the .js file and put it in the same relative directory path as the library you are typing uses
• The declare keyword tells TypeScript you are describing code that lives elsewhere