satisfies versus Pernyataan as

Fungsi as

const value = { color: "red" } as { color: string; size: number };
// No error even though size is missing!
console.log(value.color);

as Melewati Pengamanan

type Config = { color: string; size: number };
const broken = { color: "red" } as Config;
// broken.size is typed number but is actually undefined at runtime
console.log(broken.size); // undefined

satisfies Memvalidasi sebagai Pengganti

type Config = { color: string; size: number };
// const c = { color: "red" } satisfies Config; // Error: size missing
const c = { color: "red", size: 10 } satisfies Config;
console.log(c.size);

as Dapat Memaksakan Tipe yang Salah

const n = "hello" as unknown as number;
// n is typed number but is actually a string
console.log(typeof n); // "string"

satisfies Tidak Pernah Berbohong tentang Nilai

// const x = "hello" satisfies number; // Error: string not assignable to number
const y = 42 satisfies number;
console.log(y);

as Menghilangkan Pemeriksaan Properti Berlebih

type Config = { mode: string };
const withAs = { mdoe: "dark" } as Config;   // typo passes silently
// const withSat = { mdoe: "dark" } satisfies Config; // Error: mdoe
console.log(JSON.stringify(withAs));

Kapan as Benar-Benar Diperlukan

const data: unknown = JSON.parse("{ }");
// After your own runtime validation, as can express the result.
const obj = data as Record<string, unknown>;
console.log(typeof obj);

Mengutamakan satisfies untuk Konfigurasi

type Palette = Record<string, string>;
const safe = { primary: "blue", accent: "gold" } satisfies Palette;
console.log(safe.primary);

as const Itu Berbeda

type Nums = readonly number[];
const xs = [1, 2, 3] as const satisfies Nums;
console.log(xs[0]);

Ringkasan Risiko

type Config = { level: number };
// const risky = {} as Config; // compiles, level is undefined
const safe = { level: 1 } satisfies Config;
console.log(safe.level);

Memfaktorkan Ulang as menjadi satisfies

type Config = { url: string; retries: number };
// Before: const c = { url: "/api" } as Config;
const c = { url: "/api", retries: 3 } satisfies Config;
console.log(c.url, c.retries);

Pemeriksaan Singkat: satisfies vs as

Ringkasan: satisfies vs Penegasan as

type Config = { color: string; size: number };
const c = { color: "red", size: 10 } satisfies Config;
console.log(c.color, c.size);