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Typescript

• 구조 분해 할당(destructuring assignment)

  Typescript 2023. 1. 13. 20:13

  Spread syntax (...) https://ko.javascript.info/destructuring-assignment 구조 분해 할당 ko.javascript.info

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• 함수의 구조 분해 매개변수(Parameter Destructuring)

  Typescript 2023. 1. 13. 20:10

  function sum({ a, b, c }) { console.log(a + b + c); } sum({ a: 10, b: 3, c: 9 }); function sum({ a, b, c }: { a: number; b: number; c: number }) { console.log(a + b + c); }

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• 함수 인수 유형과 정의 방식

  Typescript 2023. 1. 13. 19:51

  https://www.typescriptlang.org/docs/handbook/2/functions.html Documentation - More on Functions Learn about how Functions work in TypeScript. www.typescriptlang.org

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• unknow 타입의 특성

  Typescript 2022. 12. 28. 15:38

  예제 let a:any = 123; let b:unknown = 123; let c = 123; //number console.log('a type: ' + typeof a); console.log('b type: ' + typeof b); console.log('c type: ' + typeof c); //console.log('a val: ' + (a+1)); //Err: prog.ts(10,26): error TS2365: Operator '+' cannot be applied to types 'unknown' and '1'. //console.log('b val: ' + (b+1)); //Err: prog.ts(11,26): error TS2365: Operator '+' cannot be app..

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• object 이름 얻기, constructor.name

  Typescript 2022. 12. 24. 09:39

  typeof로는 object라는 종류 값만 얻을 수 있다, class instance의 경우 class이름을 알고 싶은 경우가 있다. 예제 const collection = client.db("Db1").collection("Tb1"); console.log("db: " + client.db("Db1").constructor.name); console.log("tb: " + collection.constructor.name); 출력 db: Db tb: Collection

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• Equals Operator ( == ) vs Strict Equals Operator ( === )

  Typescript 2022. 12. 21. 21:02

  Equals Operator ( == ) vs Strict Equals Operator ( === ) 예제 //Equals Operator ( == ) vs Strict Equals Operator ( === ) console.log("10" == 10); console.log("10" === 10); console.log("10" === "10"); 결과

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• 변수 종류 확인 (타입 체크, type check)

  Typescript 2022. 12. 21. 20:57

  Equals Operator ( == ) vs Strict Equals Operator ( === ) class Ca { mA = 0; } let v1 = 123; let sb1 = Symbol("SymbolSb1"); let ca = new Ca(); console.log(typeof v1 === 'number'); //true console.log(typeof ca); //object console.log(typeof ca == 'Ca'); //false console.log(typeof ca == 'object'); //true console.log(ca instanceof Ca); //true

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• 변수 선언

  Typescript 2022. 12. 21. 19:21

  변수 종류(타입, type) 명시적 암시적 선언 typescript에서 개발자는 변수를 명시적 또는 암시적(타입 추론, type inference) 방식으로 선언한다. 암시적 Ex let myname = "john"; let phone = "007"; 명시적Ex let myname: string; let phone: number; symbol Ex let firstName = "john"; console.log(typeof firstName); let s1 = Symbol("S1"); let s2 = Symbol(); console.log(typeof s1); console.log(typeof s2); console.log(s1); console.log(s2); let s1 = Symbol("S1"); ..

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