Yaya kuke ba da jeren aiki, gami da fasallin sakonnin da alamun filin?

Question

Accepted Answer

Ka ba da jeren aiki da daruwar baci, kuma TypeScript yana goyon bayan jeren aiki na sakonnin da alamun filin da fasallin ilanti.

```ts
// basic
function add(a: number, b: number): number { return a + b; }

// optional parameter (?) — must come after required ones
function greet(name: string, title?: string): string {
  return title ? `${title} ${name}` : name; // title is string | undefined
}

// default parameter — implies optional
function inc(n: number, by: number = 1): number { return n + by; }

// rest parameter — typed as an array
function sum(...nums: number[]): number {
  return nums.reduce((a, n) => a + n, 0);
}
```

## Jeren bayanan aiki

Ka iya bayyana *alamar* aiki a matsayin nau'i — masu fa'ida ga kiran baci da masu juyawa da aiki:

```ts
type BinaryOp = (a: number, b: number) => number;
const multiply: BinaryOp = (a, b) => a * b; // params inferred from BinaryOp

// callback parameter
function apply(op: (x: number) => number, val: number) { return op(val); }
```

## Sakonnin gida (jeren alamar da yawa)

```ts
function parse(x: string): number;
function parse(x: number): string;
function parse(x: any): any { return typeof x === "string" ? +x : String(x); }
```

## Yaga haka muhimmu

Bayyana aiki ta hanya mai inganci shine ainihin ƙimar TypeScript — masu karawa suna samun jerin aiki da saniwar nau'in daruwar, fasallin sakonnin da alamun filin suna yin kwatankwatan ainihin gida, kuma jerin alamar aiki na aliasing suna ba da labari na kanta da karkatarki na jiya-odar code (kiran baci, masu sarrafa abin da ya faru, tsakiyar hanya) kuma masu aminci.