TS - type

One, basic type data

let a: number = 3let a: stringlet a: boolean

Second, the array

let a: string[] = ['jim']let a: number[]let a: boolean[]

Three, the object

let a: {name: stirng,age: number,lesson: {title: string}[]}a = {name: 'jim',age: 18,lesson: [{title: 'language'},{title: 'Math'},]}

Four, function

Set parameters and return valuesfunction sum (a: number, b: number): number {return a + b}