Annotated types and inferred types in Typescript

1. We can explicitly annotate types, annotations take the form value:type, for example:

let a: number = 1; // a is a number
let b: string = 'hello'; // b is a string
let c: boolean[] = [true, false]; // c is an array of booleans

1. We can let Typescript infer most of them for us, just leave them off and let Typescript get to work:

let a = 1; // a is a number
let b = 'hello'; // b is a string
let c = [true, false]; // c is an array of booleans

We use annotations only when necessary, keeping explicitly typed code to a minimum, and let Typescript work its inference magic for us whenever possible.