JavaScript 配列メソッドの例: 包括的なガイド (メソッド)

const arr1 = [1, 2];
const arr2 = [3, 4];
console.log(arr1.concat(arr2)); // Output: [1, 2, 3, 4]

const fruits = ['Apple', 'Banana', 'Orange'];
console.log(fruits.join(', ')); // Output: "Apple, Banana, Orange"

const numbers = [1, 2, 3, 4];
console.log(numbers.fill(0)); // Output: [0, 0, 0, 0]

const colors = ['red', 'blue', 'green'];
console.log(colors.includes('blue')); // Output: true

const numbers2 = [1, 2, 3, 2];
console.log(numbers2.indexOf(2)); // Output: 1

const letters = ['a', 'b', 'c'];
console.log(letters.reverse()); // Output: ['c', 'b', 'a']

const unsorted = [3, 1, 4, 1, 5];
console.log(unsorted.sort()); // Output: [1, 1, 3, 4, 5]

const months = ['Jan', 'March', 'April'];
months.splice(1, 0, 'Feb');
console.log(months); // Output: ['Jan', 'Feb', 'March', 'April']

const array1 = [5, 12, 8, 130, 44];
console.log(array1.at(2)); // Output: 8

const array2 = ['a', 'b', 'c', 'd', 'e'];
console.log(array2.copyWithin(0, 3, 4)); // Output: ['d', 'b', 'c', 'd', 'e']

const arr3 = [1, 2, [3, 4, [5, 6]]];
console.log(arr3.flat(2)); // Output: [1, 2, 3, 4, 5, 6]

console.log(Array.from('hello')); // Output: ['h', 'e', 'l', 'l', 'o']

const numbers3 = [5, 12, 8, 130, 44, 8];
console.log(numbers3.findLastIndex(num => num === 8)); // Output: 5

const numbers4 = [1, 2, 3];
numbers4.forEach(num => console.log(num * 2)); // Output: 2, 4, 6

const numbers5 = [1, 2, 3, 4, 5];
console.log(numbers5.every(num => num > 0)); // Output: true

const fruits2 = ['Apple', 'Banana'];
const iterator = fruits2.entries();
console.log([...iterator]); // Output: [[0, 'Apple'], [1, 'Banana']]

const fruits3 = ['Apple', 'Banana'];
const values = [...fruits3.values()];
console.log(values); // Output: ['Apple', 'Banana']

const arr4 = [1, 2, 3];
console.log(arr4.toReversed()); // Output: [3, 2, 1]
console.log(arr4); // Original array unchanged: [1, 2, 3]

const arr5 = [3, 1, 2];
console.log(arr5.toSorted()); // Output: [1, 2, 3]
console.log(arr5); // Original array unchanged: [3, 1, 2]

const arr6 = [1, 2, 3];
console.log(arr6.toSpliced(1, 1, 'two')); // Output: [1, 'two', 3]
console.log(arr6); // Original array unchanged: [1, 2, 3]

const arr7 = [1, 2, 3];
console.log(arr7.with(1, 'two')); // Output: [1, 'two', 3]
console.log(arr7); // Original array unchanged: [1, 2, 3]

async function* asyncGenerator() {
  yield 1;
  yield 2;
}
Array.fromAsync(asyncGenerator()).then(array => console.log(array)); // Output: [1, 2]

console.log(Array.of(1, 2, 3)); // Output: [1, 2, 3]

const numbers6 = [1, 2, 3];
console.log(numbers6.map(x => x * 2)); // Output: [2, 4, 6]

const arr8 = [1, 2, 3];
console.log(arr8.flatMap(x => [x, x * 2])); // Output: [1, 2, 2, 4, 3, 6]

const numbers7 = [1, 2, 3, 4];
console.log(numbers7.reduce((acc, curr) => acc + curr, 0)); // Output: 10

const numbers8 = [1, 2, 3, 4];
console.log(numbers8.reduceRight((acc, curr) => acc + curr, 0)); // Output: 10

const numbers9 = [1, 2, 3, 4, 5];
console.log(numbers9.some(num => num > 4)); // Output: true

const numbers10 = [5, 12, 8, 130, 44];
console.log(numbers10.find(num => num > 10)); // Output: 12

const numbers11 = [5, 12, 8, 130, 44];
console.log(numbers11.findIndex(num => num > 10)); // Output: 1

const numbers12 = [5, 12, 8, 130, 44];
console.log(numbers12.findLast(num => num > 10)); // Output: 44