01. 배열 속성 : length : 배열 길이 구하기 : 반환(숫자)
length 속성은 배열의 길이를 구할 수 있다.
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
//01
const arrNum = [100, 200, 300, 400, 500];
document.querySelector(".sample01_N1").innerHTML = "1";
document.querySelector(".sample01_Q1").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample01_M1").innerHTML = "length";
document.querySelector(".sample01_P1").innerHTML = arrNum.length;
//02
const arrTxt = ['a', 'b', 'c', 'd', 'f'];
document.querySelector(".sample01_N2").innerHTML = "2";
document.querySelector(".sample01_Q2").innerHTML = ['a', 'b', 'c', 'd', 'f'];
document.querySelector(".sample01_M2").innerHTML = "length";
document.querySelector(".sample01_P2").innerHTML = arrNum.length;
//03
const arr = [1, 2, ['a', 'b']];
document.querySelector(".sample01_N3").innerHTML = "3";
document.querySelector(".sample01_Q3").innerHTML = [1, 2, ['a', 'b']];
document.querySelector(".sample01_M3").innerHTML = "length";
document.querySelector(".sample01_P3").innerHTML = arr.length;
02. 배열 메서드 : join() : 배열 요소 문자열을 결합 : 반환(문자열)
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const arrNum = [100, 200, 300, 400, 500];
const text1 = arrNum.join('');
const text2 = arrNum.join(' ');
const text3 = arrNum.join('★');
const text4 = arrNum.join('-');
03. 배열 메서드 : push() / pop()
push() 메서드는 배열 마지막 요소에 추가 하고, pop() 메서드는 배열 마지막 요소를 삭제합니다.
| 번호 | 기본값 | 메서드 | 리턴값 | 결과값 |
|---|---|---|---|---|
//01
const arrNum = [100, 200, 300, 400, 500];
const arrPush = arrNum.push(600);
document.querySelector(".sample03_N1").innerHTML = "1";
document.querySelector(".sample03_Q1").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample03_M1").innerHTML = "push(600)";
document.querySelector(".sample03_P1").innerHTML = arrPush; //6 리턴값은 배열의 갯수를
document.querySelector(".sample03_A1").innerHTML = arrNum; //100,200,300,400,500,600 결과값은 전체 출력
//02
const arrNum2 = [100, 200, 300, 400, 500];
const arrPush2 = arrNum2.pop();
document.querySelector(".sample03_N2").innerHTML = "2";
document.querySelector(".sample03_Q2").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample03_M2").innerHTML = "pop()";
document.querySelector(".sample03_P2").innerHTML = arrPush2; //500 리턴값은 마지막요소를
document.querySelector(".sample03_A2").innerHTML = arrNum2; //100,200,300,400 결과값은 리턴값을 제외한 나머지를 출력
04. 배열 메서드 : unshift() / shift()
unshift() 메서드는 배열 처음 요소에 추가 shift() 배열 처음 요소에 삭제
| 번호 | 기본값 | 메서드 | 리턴값 | 결과값 |
|---|---|---|---|---|
const arrNum1 = [100, 200, 300, 400, 500];
const arrNumUnshift = arrNum1.unshift(600);
document.querySelector(".sample04_N1").innerHTML = "1";
document.querySelector(".sample04_Q1").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample04_M1").innerHTML = "unshift()";
document.querySelector(".sample04_P1").innerHTML = arrNumUnshift; // 리턴값은 배열의 갯수 6
document.querySelector(".sample04_A1").innerHTML = arrNum1; // 600,100,200,300,400,500
const arrNum2 = [100, 200, 300, 400, 500];
const arrNumshift = arrNum2.shift();
document.querySelector(".sample04_N2").innerHTML = "2";
document.querySelector(".sample04_Q2").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample04_M2").innerHTML = "shift()";
document.querySelector(".sample04_P2").innerHTML = arrNumshift; // 리턴값은 빼주는요소 100
document.querySelector(".sample04_A2").innerHTML = arrNum2; // 200,300,400,500
05. 배열 메서드 : reverse() / sort()
reverse() 메서드는 순서를 반대로 정렬 sort() 메서드는 배열 요소를 정렬
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const arrNum1 = [100, 200, 300, 400, 500];
const arrNumReverse = arrNum1.reverse();
document.querySelector(".sample05_N1").innerHTML = "1";
document.querySelector(".sample05_Q1").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample05_M1").innerHTML = "reverse()";
document.querySelector(".sample05_P1").innerHTML = arrNumReverse;
const arrNum2 = [100, 200, 300, 400, 500];
const arrNumSort2 = arrNum2.sort();
document.querySelector(".sample05_N2").innerHTML = "2";
document.querySelector(".sample05_Q2").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample05_M2").innerHTML = "sort()";
document.querySelector(".sample05_P2").innerHTML = arrNumSort2;
const arrNum3 = [100, 200, 300, 400, 500];
const arrNumSort3 = arrNum3.sort(function(a, b){return b - a});
document.querySelector(".sample05_N3").innerHTML = "3";
document.querySelector(".sample05_Q3").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample05_M3").innerHTML = "sort(function(a,b){return b-a})";
document.querySelector(".sample05_P3").innerHTML = arrNumSort3;
const arrNum4 = [500, 400, 300, 200, 100];
const arrNumSort4 = arrNum4.sort(function(a, b){return a - b});
document.querySelector(".sample05_N4").innerHTML = "4";
document.querySelector(".sample05_Q4").innerHTML = [500, 400, 300, 200, 100];
document.querySelector(".sample05_M4").innerHTML = "sort(function(a, b){return a - b})";
document.querySelector(".sample05_P4").innerHTML = arrNumSort4;
const arrNum5 = ['c', 'b', 'e', 'w', 'h'];
const arrNumSort5 = arrNum5.sort(function(a, b) { return a.localeCompare(b) });
document.querySelector(".sample05_N5").innerHTML = "5";
document.querySelector(".sample05_Q5").innerHTML = ['c', 'b', 'e', 'w', 'h'];
document.querySelector(".sample05_M5").innerHTML = "sort(function(a, b) { return a.localeCompare(b) })";
document.querySelector(".sample05_P5").innerHTML = arrNumSort5;
const arrNum6 = ['c', 'b', 'e', 'w', 'h'];
const arrNumSort6 = arrNum6.sort(function(a, b) { return b.localeCompare(a) });
document.querySelector(".sample05_N6").innerHTML = "6";
document.querySelector(".sample05_Q6").innerHTML = ['c', 'b', 'e', 'w', 'h'];
document.querySelector(".sample05_M6").innerHTML = "sort(function(a, b) { return b.localeCompare(a) })";
document.querySelector(".sample05_P6").innerHTML = arrNumSort6;
06. 배열 메서드 : concat() : 펼침연산자 | 배열요소 결합
서드는 인자로 주어진 배열이나 값들을 기존 배열에 합쳐서 새 배열을 반환합니다.
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const arrNum1 = [100, 200, 300];
const arrNum2 = [400, 500, 600];
const arrConcat = arrNum1.concat(arrNum2);
document.querySelector(".sample06_N1").innerHTML = "1";
document.querySelector(".sample06_Q1").innerHTML = "[100, 200, 300],[400, 500, 600]";
document.querySelector(".sample06_M1").innerHTML = "arrNum1.concat(arrNum2)";
document.querySelector(".sample06_P1").innerHTML = arrConcat;
const arrSpered = [ ...arrNum1, ...arrNum2 ];
document.querySelector(".sample06_N2").innerHTML = "2";
document.querySelector(".sample06_Q2").innerHTML = "[100, 200, 300],[400, 500, 600]";
document.querySelector(".sample06_M2").innerHTML = "[ ...arrNum1, ...arrNum2 ]";
document.querySelector(".sample06_P2").innerHTML = arrSpered;
07. 배열 메서드 : reduce() | reduceRight() : 배열 요소를 하나로 정리 : 반환(결괏값)
배열 요소를 하나로 정리한다.
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const arrNum1 = [100, 200, 300, 400, 500];
const arrReduce1 = arrNum1.reduce(element => element);
document.querySelector(".sample07_N1").innerHTML = "1";
document.querySelector(".sample07_Q1").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample07_M1").innerHTML = "reduce(element => element)";
document.querySelector(".sample07_P1").innerHTML = arrReduce1;
const arrNum2 = [100, 200, 300, 400, 500];
const arrReduce2 = arrNum2.reduce((p, c) => p + c);
document.querySelector(".sample07_N2").innerHTML = "2";
document.querySelector(".sample07_Q2").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample07_M2").innerHTML = "reduce((p, c) => p + c)";
document.querySelector(".sample07_P2").innerHTML = arrReduce2;
const arrNum3 = [100, 200, 300, 400, 500];
let sum = 0;
for(i=0; i<arrNum3.length; i++){
sum += arrNum3[i];
}
document.querySelector(".sample07_N3").innerHTML = "3";
document.querySelector(".sample07_Q3").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample07_M3").innerHTML = "for()";
document.querySelector(".sample07_P3").innerHTML = sum;
const arrNum4 = [[100,200], [300,400]];
const arrReduce4 = arrNum4.reduce((p, c) => p.concat(c));
document.querySelector(".sample07_N4").innerHTML = "4";
document.querySelector(".sample07_Q4").innerHTML = [[100,200], [300,400]];
document.querySelector(".sample07_M4").innerHTML = "reduce((p, c) => p.concat(c))";
document.querySelector(".sample07_P4").innerHTML = arrReduce4;
const arrNum5 = ["javascript", "react", "vue"];
const arrReduce5 = arrNum5.reduceRight((p,c) => p+c);
document.querySelector(".sample07_N5").innerHTML = "5";
document.querySelector(".sample07_Q5").innerHTML = ["javascript", "react", "vue"];
document.querySelector(".sample07_M5").innerHTML = "reduceRight((p,c) => p+c)";
document.querySelector(".sample07_P5").innerHTML = arrReduce5;
08. 배열 메서드 : slice() : 배열 요소를 다른 요소로 변경 : 반환(배열)
slice() 메서드는 배열의 새로운 배열 객체로 반환합니다.
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const arrNum = [100, 200, 300, 400, 500];
const result = arrNum.slice(2);
document.querySelector(".sample08_N1").innerHTML = "1";
document.querySelector(".sample08_Q1").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample08_M1").innerHTML = "slice(2)";
document.querySelector(".sample08_P1").innerHTML = result;
const result2 = arrNum.slice(2, 3);
document.querySelector(".sample08_N2").innerHTML = "2";
document.querySelector(".sample08_Q2").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample08_M2").innerHTML = "slice(2, 3)";
document.querySelector(".sample08_P2").innerHTML = result2;
const result3 = arrNum.slice(2, 4);
document.querySelector(".sample08_N3").innerHTML = "3";
document.querySelector(".sample08_Q3").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample08_M3").innerHTML = "slice(2, 4)";
document.querySelector(".sample08_P3").innerHTML = result3;
const result4 = arrNum.slice(2, 5);
document.querySelector(".sample08_N4").innerHTML = "4";
document.querySelector(".sample08_Q4").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample08_M4").innerHTML = "slice(2, 5)";
document.querySelector(".sample08_P4").innerHTML = result4;
const result5 = arrNum.slice(-2);
document.querySelector(".sample08_N5").innerHTML = "5";
document.querySelector(".sample08_Q5").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample08_M5").innerHTML = "slice(-2)";
document.querySelector(".sample08_P5").innerHTML = result5;
const result6 = arrNum.slice(-2, 5);
document.querySelector(".sample08_N6").innerHTML = "6";
document.querySelector(".sample08_Q6").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample08_M6").innerHTML = "slice(-2, 5)";
document.querySelector(".sample08_P6").innerHTML = result6;
09. 배열 메서드 : splice() : 배열 요소를 다른 요소로 변경 : 반환(배열)
splice() 메서드는 배열의 기존 요소를 삭제 또는 교체하거나 새 요소를 추가하여 배열의 내용을 변경합니다.
| 번호 | 기본값 | 메서드 | 리턴값 | 결과값 |
|---|---|---|---|---|
arrNum = [100, 200, 300, 400, 500];
const result = arrNum.splice(2);
document.querySelector(".sample09_N1").innerHTML = "1";
document.querySelector(".sample09_Q1").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample09_M1").innerHTML = "splice(2)";
document.querySelector(".sample09_P1").innerHTML = result;
document.querySelector(".sample09_A1").innerHTML = arrNum;
arrNum2 = [100, 200, 300, 400, 500];
const result2 = arrNum2.splice(2, 3);
document.querySelector(".sample09_N2").innerHTML = "2";
document.querySelector(".sample09_Q2").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample09_M2").innerHTML = "splice(2, 3)";
document.querySelector(".sample09_P2").innerHTML = result2;
document.querySelector(".sample09_A2").innerHTML = arrNum2;
arrNum3 = [100, 200, 300, 400, 500];
const result3 = arrNum3.splice(2, 3, 'javascript');
document.querySelector(".sample09_N3").innerHTML = "3";
document.querySelector(".sample09_Q3").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample09_M3").innerHTML = "splice(2, 3, 'javascript')";
document.querySelector(".sample09_P3").innerHTML = result3;
document.querySelector(".sample09_A3").innerHTML = arrNum3;
arrNum4 = [100, 200, 300, 400, 500];
const result4 = arrNum4.splice(1, 1, 'javascript');
document.querySelector(".sample09_N4").innerHTML = "4";
document.querySelector(".sample09_Q4").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample09_M4").innerHTML = "splice(1, 1, 'javascript')";
document.querySelector(".sample09_P4").innerHTML = result4;
document.querySelector(".sample09_A4").innerHTML = arrNum4;
arrNum5 = [100, 200, 300, 400, 500];
const result5 = arrNum5.splice(1, 0, 'javascript');
document.querySelector(".sample09_N5").innerHTML = "5";
document.querySelector(".sample09_Q5").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample09_M5").innerHTML = "splice(1, 0, 'javascript')";
document.querySelector(".sample09_P5").innerHTML = result5;
document.querySelector(".sample09_A5").innerHTML = arrNum5;
arrNum6 = [100, 200, 300, 400, 500];
const result6 = arrNum6.splice(0, 4, 'javascript');
document.querySelector(".sample09_N6").innerHTML = "6";
document.querySelector(".sample09_Q6").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample09_M6").innerHTML = "splice(0, 4, 'javascript')";
document.querySelector(".sample09_P6").innerHTML = result6;
document.querySelector(".sample09_A6").innerHTML = arrNum6;
10. 배열 메서드 : indexOf() / lastIndexOf() / includes()
slice() 메서드는 호출한 String 객체에서 주어진 값과 일치하는 첫 번째 인덱스를 반환합니다.
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const arrNum = [100, 200, 300, 400, 500];
const arrIndex = arrNum.indexOf(200);
document.querySelector(".sample10_N1").innerHTML = "1";
document.querySelector(".sample10_Q1").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample10_M1").innerHTML = "indexOf(200)";
document.querySelector(".sample10_P1").innerHTML = arrIndex;
const arrNum2 = [100, 200, 300, 400, 500];
const arrIndex2 = arrNum2.indexOf(300);
document.querySelector(".sample10_N2").innerHTML = "2";
document.querySelector(".sample10_Q2").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample10_M2").innerHTML = "indexOf(300)";
document.querySelector(".sample10_P2").innerHTML = arrIndex2;
const arrNum3 = [100, 200, 300, 400, 500];
const arrIndex3 = arrNum3.indexOf(600);
document.querySelector(".sample10_N3").innerHTML = "3";
document.querySelector(".sample10_Q3").innerHTML = [100, 200, 300, 400, 500];
document.querySelector(".sample10_M3").innerHTML = "indexOf(600)";
document.querySelector(".sample10_P3").innerHTML = arrIndex3;
const arrNum4 = [100, 200, 300, 400, 200];
const arrIndex4 = arrNum4.lastIndexOf(200);
document.querySelector(".sample10_N4").innerHTML = "4";
document.querySelector(".sample10_Q4").innerHTML = [100, 200, 300, 400, 200];
document.querySelector(".sample10_M4").innerHTML = "lastIndexOf(200)";
document.querySelector(".sample10_P4").innerHTML = arrIndex4;
const arrNum5 = [100, 200, 300, 400, 200];
const arrIndex5 = arrNum5.includes(200);
document.querySelector(".sample10_N5").innerHTML = "5";
document.querySelector(".sample10_Q5").innerHTML = [100, 200, 300, 400, 200];
document.querySelector(".sample10_M5").innerHTML = "includes(200)";
document.querySelector(".sample10_P5").innerHTML = arrIndex5;
const arrNum6 = [100, 200, 300, 400, 200];
const arrIndex6 = arrNum6.includes(600);
document.querySelector(".sample10_N6").innerHTML = "6";
document.querySelector(".sample10_Q6").innerHTML = [100, 200, 300, 400, 200];
document.querySelector(".sample10_M6").innerHTML = "includes(600)";
document.querySelector(".sample10_P6").innerHTML = arrIndex6;
11. 배열 메서드 : find() / findIndex() : 배열 요소 검색할 때 : 반환 : ★★★
find() 메서드는 주어진 판별 함수를 만족하는 첫 번째 요소의 **값**을 반환합니다. 그런 요소가 없다면 undefined를 반환합니다.
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const arrNum = [100, 200, 300, 400, 500];
// const result = arrNum.find(function(element){
// return element === 300;
// });
// const result = arrNum.find((element) => {
// return element === 300;
// });
// const result = arrNum.find(element => {
// return element === 300;
// });
const result = arrNum.find(e => e === 300);
document.querySelector(".sample11_N1").innerHTML = "1";
document.querySelector(".sample11_Q1").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample11_M1").innerHTML = "find(e => e === 300)";
document.querySelector(".sample11_P1").innerHTML = result;
const result2 = arrNum.find(e => e === 600);
document.querySelector(".sample11_N2").innerHTML = "2";
document.querySelector(".sample11_Q2").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample11_M2").innerHTML = "find(e => e === 600)";
document.querySelector(".sample11_P2").innerHTML = result2;
const arrText = ['javascript', 'jquery', 'react'];
const result3 = arrText.find(el => el === "javascript");
document.querySelector(".sample11_N3").innerHTML = "3";
document.querySelector(".sample11_Q3").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample11_M3").innerHTML = "find(el => el === 'javascript')";
document.querySelector(".sample11_P3").innerHTML = result3;
const result4 = arrText.findIndex(el => el === "javascript");
document.querySelector(".sample11_N4").innerHTML = "4";
document.querySelector(".sample11_Q4").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample11_M4").innerHTML = "findIndex(el => el === 'javascript')";
document.querySelector(".sample11_P4").innerHTML = result4;
const result5 = arrText.findIndex(el => el === "html");
document.querySelector(".sample11_N5").innerHTML = "5";
document.querySelector(".sample11_Q5").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample11_M5").innerHTML = "findIndex(el => el === 'html')";
document.querySelector(".sample11_P5").innerHTML = result5;
12. 배열 메서드 : filter() : 조건에 만족하는 배열 요소 검색할 때 : 반환(숫자) ★★★
find() 메서드와 같지만 조건을 걸수 있다.
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const arrNum = [100, 200, 300, 400, 500];
const result = arrNum.filter(el => el === 300);
document.querySelector(".sample12_N1").innerHTML = "1";
document.querySelector(".sample12_Q1").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample12_M1").innerHTML = "filter(e => e === 300)";
document.querySelector(".sample12_P1").innerHTML = result;
const arrNum2 = [100, 200, 300, 400, 500];
const result2 = arrNum2.filter(el => el === 600);
document.querySelector(".sample12_N2").innerHTML = "2";
document.querySelector(".sample12_Q2").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample12_M2").innerHTML = "filter(el => el === 600)";
document.querySelector(".sample12_P2").innerHTML = result2;
const arrNum3 = [100, 200, 300, 400, 500];
const result3 = arrNum3.filter(el => el >= 300);
document.querySelector(".sample12_N3").innerHTML = "3";
document.querySelector(".sample12_Q3").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample12_M3").innerHTML = "filter(el => el >= 300)";
document.querySelector(".sample12_P3").innerHTML = result3;
13. 배열 메서드 : map() : 배열 요소를 추출하여 새로운 배열로 만듦 : 반환(숫자)
map() 메서드는 배열 내의 모든 요소 각각에 대하여 주어진 함수를 호출한 결과를 모아 새로운 배열을 반환합니다.
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const arrNum = [100, 200, 300, 400, 500];
const result = arrNum.map(el => el);
document.querySelector(".sample13_N1").innerHTML = "1";
document.querySelector(".sample13_Q1").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample13_M1").innerHTML = "map(el => el)";
document.querySelector(".sample13_P1").innerHTML = result;
const arrNum2 = [100, 200, 300, 400, 500];
const result2 = arrNum.map(el => el + "J");
document.querySelector(".sample13_N2").innerHTML = "2";
document.querySelector(".sample13_Q2").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample13_M2").innerHTML = "map(el => el + 'J')";
document.querySelector(".sample13_P2").innerHTML = result2;
const arrNum3 = [100, 200, 300, 400, 500];
const result3 = arrNum.map(el => el + 100);
document.querySelector(".sample13_N3").innerHTML = "3";
document.querySelector(".sample13_Q3").innerHTML = "[100, 200, 300, 400, 500]";
document.querySelector(".sample13_M3").innerHTML = "map(el => el + 100)";
document.querySelector(".sample13_P3").innerHTML = result3;
const arrNum4 = [{a: 100}, {a: 200}, {a: 300}];
const result4 = arrNum4.map(el => el.a);
document.querySelector(".sample13_N4").innerHTML = "4";
document.querySelector(".sample13_Q4").innerHTML = "[{a:100}, {a:200}, {a:300}]";
document.querySelector(".sample13_M4").innerHTML = "map(el => el.a)";
document.querySelector(".sample13_P4").innerHTML = result4;
14. 배열 메서드 : Array.from() : 문자열을 배열로 반환 : 반환(결과값)
메서드는 유사 배열 객체(array-like object)나 반복 가능한 객체(iterable object)를 얕게 복사해 새로운Array 객체를 만듭니다.
| 번호 | 기본값 | 메서드 | 리턴값 |
|---|---|---|---|
const text = "javascript";
const result = Array.from(text);
document.querySelector(".sample14_N1").innerHTML = "1";
document.querySelector(".sample14_Q1").innerHTML = "javascript";
document.querySelector(".sample14_M1").innerHTML = "Array.from(text)";
document.querySelector(".sample14_P1").innerHTML = result;
console.log(result);
const text2 = "javascript";
const result2 = Array.from(text2, el => el + "10");
document.querySelector(".sample14_N2").innerHTML = "2";
document.querySelector(".sample14_Q2").innerHTML = "javascript";
document.querySelector(".sample14_M2").innerHTML = "Array.from(text2, el => el + '10')";
document.querySelector(".sample14_P2").innerHTML = result2;
console.log(result2);
const text3 = "javascript";
const result3 = [...text3].map(el => el);
document.querySelector(".sample14_N3").innerHTML = "3";
document.querySelector(".sample14_Q3").innerHTML = "javascript";
document.querySelector(".sample14_M3").innerHTML = "[...text3].map(el => el)";
document.querySelector(".sample14_P3").innerHTML = result3;