push() : 뒤에 삽입 / pop() : 뒤에 삭제
unshift() : 앞에 삽입 / shift() : 앞에 삭제
let arr = [1, 2, 3, 4, 5];
arr.splice(1, 2);
console.log(arr);
let arr = [1, 2, 3, 4, 5];
arr.splice(1, 3, 100, 200);
console.log(arr);
let arr2 = ["나는", "철수", "입니다"];
arr2.splice(1, 0, "대한민국", "소방관");
console.log(arr2);
let arr = [1, 2, 3, 4, 5];
let result = arr.splice(1, 2);
console.log(arr);
console.log(result);
let arr = [1, 2, 3, 4, 5];
let result = arr.slice(1, 4);
console.log(result);
let arr2 = arr.slice();
console.log(arr2);
let arr = [1, 2];
console.log(arr.concat([3, 4]));
console.log(arr.concat([3, 4], [5, 6]));
console.log(arr.concat([3, 4], 5, 6));
let users = ['Mike', 'Tom', 'Jane'];
users.forEach((name, index) => {
console.log(name);
console.log(`${index+1}. ${name}`);
});
let arr = [1, 2, 3, 4, 5, 1, 2, 3];
console.log(arr.indexOf(3));
console.log(arr.indexOf(6));
console.log(arr.indexOf(3, 3));
console.log(arr.lastIndexOf(3));
let arr = [1, 2, 3];
console.log(arr.includes(2));
console.log(arr.includes(8));
let arr = [1, 2, 3, 4, 5];
const result = arr.find((item)=>{
return item % 2 === 0;
});
console.log(result);
let userList = [
{ name: "Mike", age: 30 },
{ name: "Jane", age: 27 },
{ name: "Tom", age: 10 }
];
const result2 = userList.find((user) => {
if(user.age<19){
return true;
}
return false;
});
console.log(result2);
const result3 = userList.findIndex((user) => {
if(user.age<19){
return true;
}
return false;
});
console.log(result3);
let arr = [1, 2, 3, 4, 5, 6];
const result = arr.filter((item)=>{
return item % 2 === 0;
});
console.log(result);
let arr = [1, 2, 3, 4, 5];
const result = arr.reverse();
console.log(result);
let userList = [
{ name: "Mike", age: 30 },
{ name: "Jane", age: 27 },
{ name: "Tom", age: 10 }
];
let newUserList = userList.map((user, index) => {
return Object.assign({}, user, {
id: index +1,
isAdult: user.age > 19
});
});
console.log(newUserList);
console.log(userList);
let arr = ["안녕", "나는", "철수야"];
let result = arr.join();
console.log(result);
let result2 = arr.join(' ');
console.log(result2);
const users = "Mike,Jane,Tom,Tony";
const result = users.split(',');
console.log(result);
let str = 'Hello, My name is Mike';
const result = str.split('');
console.log(result);
let user = {
name: 'Mike',
age: 30
};
let userList = ["Mike", "Tom", "Jane"];
console.log(typeof user);
console.log(typeof userList);
console.log(Array.isArray(user));
console.log(Array.isArray(userList));