Javaエンジニアが始めるTypeScript入門（第4回：その他の基本型）

//anyをそのまま操作
let any1_1: any = { id: 1, name: "suzuki", fn: (): string => { return "hoge"; } };
any1_1.id; //*1
any1_1.fn();
any1_1.id = 2; //{ id: 2, name: "suzuki" }
any1_1.id = "hoge";  //異なる型で更新 *2

//型アサーションしてanyを操作
let any1_2: any = { id: 1, name: "suzuki", fn: (): string => { return "hoge"; } };
(any1_2 as { id: number }).id; //*3

//型ガードで型を特定したanyを操作
const isPerson = (obj: any): obj is Person => {
  return obj instanceof Person;
};
let any2: any = new Person(1, "suzuki");
if (isPerson(any2)) { //*4
  any2.id;
  any2.fn();
  any2.id = 2;
} else if (typeof any2 === "string") {
  any2.length;
}

//型を明示している変数にanyを代入してみる
let any3_1: number = 1;
let any3_2: any = "hoge";
any3_1 = any3_2; //any3_1=hoge, typeof any3_1=string *5

//anyにいろいろな型の値を代入してみる
let any4;
any4 = 10; //typeof any4=number *6
any4 = "hoge"; //typeof any4=string
any4 = 10n; //typeof any4=bigint
any4 = { id: 1, name: "suzuki" }; //typeof any4=object
// let any4_1: string = any4; //*7

// Objectが近いので、Objectを使って例示します。

@AllArgsConstructor
@Getter
@Setter
class Person {
  private Object id;
  private Object name;
  String fn() {return "hoge";}
}

// 「anyをそのまま操作」「型アサーションしてanyを操作」の代替 *1
Object any1 = new Person(1, "suzuki");
((Person) any1).getId();
((Person) any1).fn();
((Person) any1).setId(2);
((Person) any1).setId("hoge");

// 型ガードで型を特定したanyを操作
Object obj2 = new Person(1, "suzuki");
if (obj2 instanceof Person) {
  Person obj2_p = (Person) obj2;
  obj2_p.getId();
  obj2_p.fn();
  obj2_p.getName();
} else if (obj2 instanceof String) {
  String obj2_s = (String)obj2;
  obj2_s.length();
}

// 型を明示している変数にanyを代入してみる *2
// anyにいろいろな型の値を代入してみる *2

//型アサーションしてobjectを操作
let obj1: object = { id: 1, name: "suzuki", fn: (): string => { return "hoge"; } };
// obj1.id; //*1
(obj1 as { id: number }).id; //*2
(obj1 as { fn: () => {} }).fn(); //*2
(obj1 as { id2: number }).id2; //undefined *3
(obj1 as { id2: number }).id2 = 2; //{ id: 1, name: 'suzuki', fn: [Function: fn], id2: 2 } *4

//型ガードで型を特定したobjectを操作
let obj2: object = new Person(1, "suzuki");
if (obj2 instanceof Person) { //*5
  obj2.id;
  obj2.fn();
  obj2.id = 2;
} else if (typeof obj2 === "string") {
  // obj2.length; //never *6
}

//型を明示している変数にobjectを代入してみる
let obj3_1: number = 1;
let obj3_2: object = { id: 1 };
// obj3_1 = obj3_2; //*7

//objectにいろいろな型の値を代入してみる
let obj4: object;
// obj4 = 1; //*6
obj4 = { id: 1 };
obj4 = [1, 2, 3];
obj4 = () => {return "hoge"};

// Objectが近い型と言えます。

//スプレッド演算子による合成
let objSp1_1 = {id: 1, name: "suzuki"};
let objSp1_2 = {address: "tokyo"};
let objSp1_3 = {name: "sato", address: "tokyo"};
let objSp12 = {...objSp1_1, ...objSp1_2}; //{"id":1,"name":"suzuki","address":"tokyo"}
let objSp13 = {...objSp1_1, ...objSp1_3}; //{"id":1,"name":"sato","address":"tokyo"} *1
//合成元への変更の波及を確認
objSp13.name = "takahashi"; // objSp1_2={"name":"sato","address":"tokyo"}, objSp13={"id":1,"name":"takahashi","address":"tokyo"} *2
//合成先への変更の波及を確認
objSp1_3.name = "yamaguchi"; // objSp2={"name":"yamaguchi","address":"tokyo"}, objSp13={"id":1,"name":"takahashi","address":"tokyo"} *3

// 結合対象がMapとした場合のコード例
Map<String, Object> objSp1_1 = new HashMap<>() {{
  put("id", 1);
  put("name", "suzuki");
}};
Map<String, Object> objSp1_2 = new HashMap<>() {{
  put("address", "tokyo");
}};
Map<String, Object> objSp1_3 = new HashMap<>() {{
  put("name", "sato");
  put("address", "tokyo");
}};
Map<String, Object> objSp12 = new HashMap<>() {{ //{name=suzuki, id=1, address=tokyo}
  putAll(objSp1_1);
  putAll(objSp1_2);
}};
Map<String, Object> objSp13 = new HashMap<>() {{ //{name=sato, id=1, address=tokyo}
  putAll(objSp1_1);
  putAll(objSp1_3);
}};
//合成元への変更の波及を確認
objSp13.put("name", "takahashi"); //objSp1_3={address=tokyo, name=sato}, objSp13={name=takahashi, id=1, address=tokyo}
//合成先への変更の波及を確認
objSp1_3.put("name", "yamaguchi"); //objSp1_3={address=tokyo, name=yamaguchi}, objSp13={name=takahashi, id=1, address=tokyo}

// 分割代入
const objDivide = {id: 1, name: "suzuki", address: "tokyo"};
const {id, address} = objDivide; //id=1, address=tokyo

// 分割代入＋スプレッド演算子
const objDivide2 = {first: 1, second: 2, third: 3, forth: 4, fifth: 5};
const {first, second, ...rest} = objDivide2; //first=1, second=2, rest={"third":3,"forth":4,"fifth":5}

// 異なる変数名を定義
const {first: iti, second: ni} = objDivide2; //iti=1, ni=2

// 分割代入に対応する機能はありません。

class Person {
  id: number = 0;
  name: string = "";

  constructor(id: number, name: string) {
    this.id = id;
    this.name = name;
  }

  fn() {
    console.log("Person#fn");
  };
}

//型アサーションしてunknownを操作
let unk1: unknown = { id: 1, name: "suzuki", fn: (): string => { return "hoge"; } };
// unk1.id; //*1
(unk1 as { id: number }).id; //*2
(unk1 as { fn: () => {} }).fn(); //*2
(unk1 as { id2: number }).id2; //undefined *3

//型ガードで型を特定したunknownを操作
let unk2: unknown = new Person(1, "suzuki");
if (unk2 instanceof Person) { //*4
  unk2.id;
  unk2.fn();
  unk2.id = 2;
} else if (typeof unk2 === "string") {
  unk2.length; //stringが持つ関数
} else if (typeof unk2 === "number") {
  unk2 * 2; //numberを積算
}

//型を明示している変数にunknownを代入してみる
let unk3_1: number = 1;
let unk3_2: unknown = 2;
// unk3_1 = unk3_2; //*5

//unknownにいろいろな型の値を代入してみる
let unk4: unknown;
unk4 = "hoge"; //typeof unk4=string *6
unk4 = 1; //typeof unk4=number

// Objectが近い型と言えます。

const fnVoid = (): void => {};
const fnVoidInf = () => {};

void fnVoid() {}
void fnVoidInf() {}

const nv0_1: any = 1;
// const nv0_2: never = nv0_1; //*1
const nv1: never = 1 as never; //*2
const nv2 = 1 as never;
const nv2_1: string = nv2; //*3
const nv2_2: number = nv2;

//対応する型はありません。

enum Enum1 {
  ONE,
  TWO,
  THREE,
}

//単数の値を持つEnum
enum Enum2 {
  ONE = 1,
  TWO = 2,
  THREE = 3,
}

//複数の値を持つEnumっぽいもの *1
type Enum3 = {
  [K in "ONE" | "TWO" | "THREE"]: {
    value: number;
    viewString: string;
  };
};
//Enum3={ONE: {value: number;viewString: string;}; TWO: {value: number;viewString: string;}; THREE: : {value: number;viewString: string;};}
const enum3: Enum3 = {
  ONE: { value: 1, viewString: "いち" },
  TWO: { value: 2, viewString: "に" },
  THREE: { value: 3, viewString: "さん" },
};
//enum3.ONE.value=1, enum3.ONE.viewString="いち"

enum Enum1 {
  ONE,
  TWO,
  THREE,
}

//単数の値を持つEnum
@AllArgsConstructor
enum Enum2 {
  ONE(1), TWO(2), THREE(3);

  private int value;
}

//複数の値を持つEnum
@AllArgsConstructor
enum Enum3 {
  ONE(1, "いち"), TWO(2, "に"), THREE(3, "さん");

  private int value;
  private String viewString;
}