Type-Variables-In-Ts

Type Variables in TypeScript

Source

In TypeScript you have the ability to pass in generics as stand ins for other types. So for example

function identity<Type>(arg: Type): Type {
  return arg;
}

The identity function will take in the special generic variable, denoted using the <> angle brackets, and that will serve as a stand in for other types you pass in.

For example

let output = identity("this is an output string");

console.log("Type ID function return: " + output);

The output variable will use the function and pass in a string. The compiler will look at this string and infer the string argument's type as type to be returned.

Alternatively you can write the above like:

let output = identity<string>("This is a string return");

Which explicitely passes in the return type using the <> angle brackets. The first solution is cleaner but for more complicated cases this might be better to go with.

#JavaScript
#TypeScript