unshift():從數組中新增（添加）第一個元素並返回新增的元素。

const array1 = [1, 2, 3]; 
const firstElement = array1.unshift(0);
console.log(array1);
//(4) [0, 1, 2, 3]
console.log(firstElement);
//4

every():所有元素符合…

const people = [
    { name: 'Wes', year: 1988 },
    { name: 'Kait', year: 1986 },
    { name: 'Irv', year: 1970 },
    { name: 'Lux', year: 2015 },
]
const isEvery=people.every((person)=>{
   const currentYear= new Date().getFullYear();
  return currentYear - person.year >= 19;
})
//console.log('是否全部人都超過19歲的人',isEvery)
//false

flat():創建一個新數組，其中所有子數組元素以遞歸方式連接到指定深度。

const arr1 = [0, 1, 2, [3, 4]];
console.log(arr1.flat());
//Array [0,1,2,3,4]

const arr2 = [0, 1, 2, [[[3, 4]]]];
console.log(arr2.flat(2));
//Array [0, 1, 2, Array [3, 4]]

some():至少一個元素符合…

const people = [
    { name: 'Wes', year: 1988 },
    { name: 'Kait', year: 1986 },
    { name: 'Irv', year: 1970 },
    { name: 'Lux', year: 2015 },
]
const isSome=people.every((person)=>{
   const currentYear= new Date().getFullYear();
  return currentYear - person.year >= 19;
})
//console.log('至少一個19歲的人',isSome)
//true

const array = [1, 2, 3, 4, 5];

// 檢查元素是否為偶數(%2:是否餘2)
const even = (element) => element % 2 === 0;

const someEven=array.some(even);
console.log(someEven);
//true

fill(填充數據,位置開始,結束)

const array1 = [1, 2, 3, 4];
//從位置 2 到位置 4 填充 0
console.log(array1.fill(0, 2, 4));
//[1,2,0,0]

//從位置 1 填充 5
console.log(array1.fill(5, 1));
//[1,5,5,5]

//填充6
console.log(array1.fill(6));
// [6, 6, 6, 6]

concat():合併兩個或多個數組

const array1 = ['a', 'b', 'c'];
const array2 = ['d', 'e', 'f'];
const array3 = array1.concat(array2);
console.log(array3);
// Array ["a", "b", "c", "d", "e", "f"]

push()：將一個或多個元素添加到數組

const animals = ['pigs', 'goats', 'sheep'];

const count = animals.push('cows');
console.log(count);//4
console.log(animals);//["pigs","goats","sheep","cows"]

pop()刪除最後一個元素並返回該元素

const plants = ['broccoli', 'cauliflower', 'cabbage', 'kale', 'tomato'];

console.log(plants.pop());
// "tomato"

console.log(plants);
// ["broccoli", "cauliflower", "cabbage", "kale"]

keys():返回一個新的Array Iterator對象，其中包含數組中每個索引的鍵

const array1 = ['a', 'b', 'c'];
const iterator = array1.keys();

for (const key of iterator) {
  console.log(key);
}
//0
//1
//2

Math.round():四捨五入

Math.round(3.14)      // 3
Math.round(5.49999)   // 5
Math.round(5.5)       // 6
Math.round("5.50001") // 6
Math.round(-5.49999)  // -5
Math.round(-5.5)      // -5
Math.round(-5.50001)  // -6