const date1 = new Date();
console.log(date1); // Fri Jun 02 2023 21:57:16 GMT+0900 (한국 표준시)
const date2 = new Date(2022, 11, 16, 17, 12, 57, 30);
console.log(date2); // Fri Dec 16 2022 17:12:57 GMT+0900 (한국 표준시)
const date3 = new Date("December 17, 1995 03:24:00");
console.log(date3); // Sun Dec 17 1995 03:24:00 GMT+0900 (한국 표준시)
const date = new Date();
console.log(date); // Fri Jun 02 2023 21:58:15 GMT+0900 (한국 표준시)
console.log(date.getFullYear()); // 2023
date.setFullYear(2020);
console.log(date); // Tue Jun 02 2020 21:58:15 GMT+0900 (한국 표준시)
console.log(date.getFullYear()); // 2020
const date = new Date();
console.log(date); // Fri Jun 02 2023 21:58:58 GMT+0900 (한국 표준시)
console.log(date.getMonth()); // 5
date.setMonth(0);
console.log(date); // Mon Jan 02 2023 21:58:58 GMT+0900 (한국 표준시)
console.log(date.getMonth()); // 0
const date = new Date();
console.log(date); // Fri Jun 02 2023 21:59:44 GMT+0900 (한국 표준시)
console.log(date.getDate()); // 2
date.setDate(11);
console.log(date); // Sun Jun 11 2023 21:59:44 GMT+0900 (한국 표준시)
console.log(date.getDate()); // 11
const date = new Date();
console.log(date); // Fri Jun 02 2023 22:00:38 GMT+0900 (한국 표준시)
console.log(date.getHours()); // 22
date.setHours(19);
console.log(date); // Fri Jun 02 2023 19:00:38 GMT+0900 (한국 표준시)
console.log(date.getHours()); // 19
const date = new Date();
console.log(date); // Fri Jun 02 2023 22:01:20 GMT+0900 (한국 표준시)
console.log(date.getMinutes()); // 1
date.setMinutes(48);
console.log(date); // Fri Jun 02 2023 22:48:20 GMT+0900 (한국 표준시)
console.log(date.getMinutes()); // 48
const date = new Date();
console.log(date); // Fri Jun 02 2023 22:02:01 GMT+0900 (한국 표준시)
console.log(date.getSeconds()); // 1
date.setSeconds(58);
console.log(date); // Fri Jun 02 2023 22:02:58 GMT+0900 (한국 표준시)
console.log(date.getSeconds()); // 58
const date = new Date();
const day = date.getDay();
console.log(date); // Fri Jun 02 2023 22:02:40 GMT+0900 (한국 표준시)
console.log(day); // 5
console.log(getDayKo(day)); // 금요일
function getDayKo(day) {
switch (day) {
case 0:
return "일요일";
case 1:
return "월요일";
case 2:
return "화요일";
case 3:
return "수요일";
case 4:
return "목요일";
case 5:
return "금요일";
case 6:
return "토요일";
}
}
const date = new Date();
console.log(date); // Fri Jun 02 2023 22:03:21 GMT+0900 (한국 표준시)
console.log(date.getTime()); // 1685711001119
date.setTime(170000000000);
console.log(date); // Thu May 22 1975 23:13:20 GMT+0900 (한국 표준시)
console.log(date.getTime()); // 170000000000
Date.prototype.isAfter = function (date) {
const a = this.getTime();
const b = date.getTime();
return a > b;
};
const date1 = new Date("Fri Jun 02 2023 21:00:00 GMT+0900 (한국 표준시)");
const date2 = new Date("Fri Jun 02 2023 22:00:00 GMT+0900 (한국 표준시)");
console.log(date1.isAfter(date2)); // false
console.log(date2.isAfter(date1)); // true
const time = new Date().getTime();
console.log(Date.now()); // 1685711180711
console.log(time); // 1685711180711
setTimeout(() => {
console.log(Date.now()); // 1685711181716
console.log(time); // 1685711180711
}, 1000);
const target = { a: 1, b: 2 };
const source1 = { b: 3, c: 4 };
const source2 = { c: 5, d: 6 };
const result = Object.assign(target, source1, source2);
console.log(target); // { a: 1, b: 3, c: 5, d: 6 }
console.log(result); // { a: 1, b: 3, c: 5, d: 6 }
const target = { a: 1, b: 2 };
const source1 = { b: 3, c: 4 };
const source2 = { c: 5, d: 6 };
const result1 = Object.assign({}, target, source1, source2);
const result2 = { ...target, ...source1, ...source2 };
console.log(target); // { a: 1, b: 2 }
console.log(result1); // { a: 1, b: 3, c: 5, d: 6 }
console.log(result2); // { a: 1, b: 3, c: 5, d: 6 }
const user = {
name: "hong",
age: 100,
isValid: true,
};
console.log(Object.entries(user));
// [["name", "hong"], ["age", 100], ["isValid", true] ]
for (const [key, value] of Object.entries(user)) {
console.log(key, value);
}
const user = {
name: "hong",
age: 100,
isValid: true,
email: "hong@gmail.com",
};
console.log(Object.keys(user)); // ['name', 'age', 'isValid', 'email']
const user = {
name: "hong",
age: 100,
isValid: true,
email: "hong@gmail.com",
};
console.log(Object.values(user)); // ['hong', 100, true, 'hong@gmail.com']
JSON.stringify(data)
- json 데이터를 문자열로 변환합니다.
- 입력타입 : String, Number, Boolean, Null, Object, Array
- 반환타입 : String
JSON.parse(data)
- 문자열을 json 데이터로 변환합니다.
- 입력타입 : String
- 반환타입 : String, Number, Boolean, Null, Object, Array
console.log(JSON.stringify("Hello world!")); // "Hello world!"
console.log(JSON.stringify(123)); // 123
console.log(JSON.stringify(false)); // false
console.log(JSON.stringify(null)); // null
console.log(JSON.stringify({ name: "hong", age: 100 })); // {"name":"hong","age":100}
console.log(JSON.stringify([1, 2, 3])); // [1,2,3]
console.log(JSON.parse('"Hello world!"')); // Hello world!
console.log(JSON.parse("123")); // 123
console.log(JSON.parse("false")); // false
console.log(JSON.parse("null")); // null
console.log(JSON.parse('{ "name": "hong", "age": 100 }')); // {name: 'hong', age: 100}
console.log(JSON.parse("[1, 2, 3]")); // [1, 2, 3]