- arr.splice(n,m): ํน์ ์์ ์ง์
n-> ์์ / m -> ๊ฐ์
let arr = [1,2,3,4,5];
arr.splice(1,2);
console.log(arr); //[1,4,5]
- arr.splice(n,m,x): ํน์ ์์ ์ง์ฐ๊ณ ์ถ๊ฐ
let arr = [1,2,3,4,5];
arr.splice(1,3,100,200);
console.log(arr); //[1,100,200,5]
-> m ์๋ฆฌ์ 0์ด ๋ค์ด๊ฐ ๊ฒฝ์ฐ ์ ๊ฑฐํ ์ ์๋ ์ซ์ ๊ฐฏ์ ์์ด x๋ฅผ ์ถ๊ฐํจ
let arr = ["๋๋", "์ถ", "์
๋๋ค"]
arr.splice(1,0,"๋ํ๋ฏผ๊ตญ", "์ฌ๋");
console.log(arr); //["๋๋","๋ํ๋ฏผ๊ตญ","์ฌ๋","์ถ","์
๋๋ค"]
- arr.splice(): ์ญ์ ๋ ์์ ๋ฐํ
let arr = [1,2,3,4,5];
let result = arr.splice(1,2);
console.log(arr); //[1,4,5]
console.log(result);//[2,3]
-arr.slice(n,m): n๋ถํฐ m๊น์ง ๋ฐํ
let arr = [1,2,3,4,5];
arr.slice(1,4); //[2,3,4]
-> ๋ง์ฝ ๊ดํธ์์ ์๋ฌด ๊ฒ๋ ์๋ ๊ฒฝ์ฐ ๋ด์ฉ ๊ทธ๋๋ก ๋ณต์ฌ๋จ
let arr2 = arr.slice();
console.log(arr2); //[1,2,3,4,5]
- arr.concat(arr2, arr3 ...): ํฉ์ณ์ ์ ๋ฐฐ์ด ๋ฐํ
let arr = [1,2];
arr.concat([3,4]); //[1,2,3,4]
arr.concat([3,4],[5,6]); //[1,2,3,4,5,6]
->[3,4]๋ ๋ฐฐ์ด 5,6์ ๊ฐ๊ฐ ๋ฐํํ ๊ฒฝ์ฐ
let arr = [1,2]
arr.concat([3,4],5,6); //[1,2,3,4,5,6]
-arr.forEach(fn): ๋ฐฐ์ด ๋ฐ๋ณต, ํจ์๋ฅผ ์ธ์๋ก ๋ฐ์
let users = ['Mike','Tom','jane'];
users.forEach((item, index, arr) => {});
ํจ์์ ์ด 3๊ฐ์ ๋งค๊ฐ๋ณ์๊ฐ ์์
item: ํด๋น ์์
index: ํด๋น index
arr:ํด๋น ๋ฐฐ์ด ์์ฒด
//forEach
let arr = ["Mike","Tom","Jane"];
arr.forEach((name, index) => {
console.log(`${index +1 }. ${name}`);
});
//1.Mike
//2.Tom
//3.Jane
index๋ 0 ๋ถํฐ ์์ํ๋๋ฐ 1 ์ถ๊ฐํ๋ฉด์ 1๋ถํฐ ํ์๊ฐ ๋จ
์์) ๋ฐฐ์ด์ ๋ชจ๋ ์ ํฉ์น๊ธฐ
let arr = [1,2,3,4,5];
let result = 0;
arr.forEach((num) => {
result += num;
});
console.log(result); //15
-arr.indexOf / arr.lastIndexOf: ๋ฌธ์์ด array ์ ์ฌ์ฉ๋ฒ์ ๊ฐ์
์ผ๋ฐ์ ๋ฐฐ์ด์์ ๊ฐ์ ํด๋นํ๋ index๋ฅผ ๋ฐํ
์์ ๊ฒฝ์ฐ -1๋ก ๋ฐํ
let arr = [1,2,3,4,5,1,2,3];
console.log(arr.indexOf(3); //2
console.log(arr.indexOf()); //-1
์ธ์๊ฐ 2๊ฐ์ผ ๊ฒฝ์ฐ ๋๋ฒ์งธ ๊ฐ์ ์์ ์์น ์๋ฏธ
let arr = [1,2,3,4,5,1,2,3];
console.log(arr.indexOf(3,3)); //7
๋์์๋ถํฐ ํ์ํ๊ณ ์ถ์ ๊ฒฝ์ฐ lastIdexOf ์ฌ์ฉ
let arr = [1,2,3,4,5,1,2,3];
console.log(arr.lastIndexOf(3)); //7
-arr.includes(): ํฌํจํ๋์ง ํ์ธ
let arr = [1,2,3];
console.log(arr.includes(2)); //true
console.log(arr.includes(5)); //false
- arr.find(fn) / arr.findIndex(fn): ๋ณด๋ค ๋ณต์กํ ์ฐ์ฐ์ด ๊ฐ๋ฅํ๋๋ก ํจ์๋ฅผ ์ฌ์ฉ
์ฒซ๋ฒ์งธ true ๊ฐ๋ง ๋ฐํํ๊ณ ๋๋จ. ๋ง์ฝ ์์ผ๋ฉด undefined๋ฅผ ๋ฐํ
findIndex๋ ํด๋น index๋ฅผ ๋ฐํํ๊ณ ์๋ ๊ฒฝ์ฐ -1 ๋ฐํ
์์) ์ง์ ์ฐพ์๋ด๊ธฐ
let arr = [1,2,3,4,5];
const result = arr.find((item) => {
return item % 2 === 0;
});
console.log(result); //2
์์) ๊ฐ์ฒด๊ฐ ๋ค์ด์๋ ๋ฐฐ์ด
let userList = [
{ name: "Mike", age: 30 },
{ name: "Jane", age: 27 },
{ name: "Tom", age: 10 },
];
const result = userList.find((user) => {
if (user.age < 19){
return true;
}
return false;
});
console.log(result) //{name: 'Tom', age: 10}
const result = userList.findIndex((user) => {
if (user.age < 19){
return true;
}
return false;
});
console.log(result) //2
- arr.filter(fn): ๋ง์กฑํ๋ ๋ชจ๋ ์์๋ฅผ ๋ฐฐ์ด๋ก ๋ฐํ
find์ ์ฌ์ฉ ๋ฐฉ๋ฒ ๋์ผ
let arr = [1,2,3,4,5,6];
const result = arr.filter((item) => {
return item % 2 === 0;
});
console.log(result); //(3)[2,4,6]
- arr.reverse(): ๋ฐฐ์ด์ ์ญ์์ผ๋ก ์ฌ์ ๋ ฌ. ์ต๊ทผ ๊ฐ์ ์ ํน์ ์ต๊ทผ ๊ฒ์ ์ ๋ ฌ
let arr = [1,2,3,4,5];
console.log(arr.reverse()); //(5)[5,4,3,2,1]
- arr.map(fn): ํจ์๋ฅผ ๋ฐ์ ํน์ ๊ธฐ๋ฅ์ ์ํํ๊ณ ์๋ก์ด ๋ฐฐ์ด ๋ฐํ
let userList = [
{ name: "Mike", age: 30 },
{ name: "Jane", age: 27 },
{ name: "Tom", age: 10 },
];
let newUserList = userList.map((user,index) => {
return Object.assign({},user, {
isAdult: user.age > 19,
});
});
console.log(newUserList);
console.log(userList);

- arr.join: ๋ฐฐ์ด์ ํฉ์ณ์ ๋ฌธ์์ด ๋ง๋ฆ
() ์์ ์๋ฌด ๊ฒ๋ ๋ฃ์ง ์์ ๊ฒฝ์ฐ ๋ฌธ์์ ๋ฌธ์ ์ฌ์ด , ๋ก ํ์๋จ
let arr = ["์๋
", "๋๋", "์ฒ ์์ผ"];
let result = arr.join();
console.log(result); //์๋
,๋๋,์ฒ ์์ผ
(" ")์์ ๋ฃ์ ๋๋ก ๋ฌธ์ ์ฌ์ด์ ์ถ๋ ฅ ๋จ. ๋์ด์ฐ๊ธฐ(๊ณต๋ฐฑ) ๋ฃ์ผ๋ฉด ๊ณต๋ฐฑ ๊ทธ๋๋ก ๋ณด์ฌ์ค
let arr = ["์๋
", "๋๋", "์ฒ ์์ผ"];
let result = arr.join(" ");
console.log(result); //์๋
๋๋ ์ฒ ์์ผ
- split: ๋ฌธ์์ด์ , ๊ธฐ์ค์ผ๋ก ๋๋ ์ ๋ฐฐ์ด์ ๋ง๋ค์ด์ค
const users = "Mike,Jane,Tom,Tony";
const result = users.split(",");
console.log(result); //(4) ['Mike', 'Jane', 'Tom', 'Tony']
(" ") ์์ ์๋ฌด ๊ฒ๋ ์์ ๊ฒฝ์ฐ ๋น ๋ฌธ์ ๊ธฐ์ค์ผ๋ก ๋๋์ด์ค
let str = "Hello, My name is Mike.";
const result = str.split("");
console.log(result);
// ['H', 'e', 'l', 'l', 'o', ',', ' ', 'M', 'y', ' ', 'n', 'a', 'm', 'e', ' ', 'i', 's', ' ', 'M', 'i', 'k', 'e', '.']
- Array.isArray: ๋ฐฐ์ด์ธ์ง ์๋์ง ํ์ธ ๊ฐ๋ฅ
let user = {
name: "Mike",
age: 30,
}; //๊ฐ์ฒด
let userList = ["Mike", "Tom", "Jane"]; //๋ฐฐ์ด
console.log(Array.isArray(user)); //false
console.log(Array.isArray(userList)); //true
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