Math.sin():

function getCircleY(radians, radius) {
  return Math.sin(radians) * radius;
}

console.log(getCircleY(1, 10));
// Expected output: 8.414709848078965

console.log(getCircleY(2, 10));
// Expected output: 9.092974268256818

console.log(getCircleY(Math.PI, 10));
// Expected output: 1.2246467991473533e-15

Math.sqrt():

Math.sqrt(x)=√￣＝the unique y>=0 such that y2=x

function calcHypotenuse(a, b) {
  return (Math.sqrt((a * a) + (b * b)));
}

console.log(calcHypotenuse(3, 4));
// Expected output: 5

console.log(calcHypotenuse(5, 12));
// Expected output: 13

console.log(calcHypotenuse(0, 0));
// Expected output: 0

Math.trunc() 去掉小數部分

Math.trunc(13.37)    // 13
Math.trunc(42.84)    // 42
Math.trunc(0.123)    //  0
Math.trunc(-0.123)   // -0
Math.trunc("-1.123") // -1

replace():取代(首個)…

//方法會傳回一個新字串，此新字串是透過將原字串與 pattern 比對，以 replacement 取代吻合處而生成

const p = 'The quick brown fox jumps over the lazy dog. If the dog reacted, was it really lazy?';
const p
const pReplace=p.replace('dog', 'monkey');
console.log('Ｐreplace',pReplace);
//"The quick brown fox jumps over the lazy monkey. If the dog reacted, was it really lazy?"

replaceAll()取代所有…

const p = 'The quick brown fox jumps over the lazy dog. If the dog reacted, was it really lazy?';
const  pReplaceAll=p.replaceAll('dog', 'monkey');
console.log('ＰreplaceAll',pReplaceAll);
//"The quick brown fox jumps over the lazy monkey. If the monkey reacted, was it really lazy?"
const regex = /Dog/ig;
console.log(p.replaceAll(regex, 'ferret'));
//"The quick brown fox jumps over the lazy ferret. If the ferret reacted, was it really lazy?"

shift():從數組中刪除第一個元素並返回刪除的元素。

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

參數（第一個參數,數量,數據）
第一個參數可以是字串，數字，
第二個參數一定是數量：0～…
第三個參數可以是字串，數字：如果有為取代，如果沒有為新增

刪除

const arr =["apple","book","phone"]
const arrSplice=arr.splice("apple",1);
console.log('arrSplice',arrSplice);
//arrSplice ["apple"]
console.log('arr',arr);
//arr ["book","phone"]

取代

const arry =["apple","book","phone"];
const  arrySplice=arry.splice("apple",1,"spack");
console.log('arrySplice',arrySplice);
//"arrySplice" ["apple"]
console.log('arry',arry);
//"arry" ["spack","book","phone"]

新增

const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.splice(2,0,"Lemon","Kiwi");
console.log('fruits',fruits);
//"fruits" ["Banana","Orange","Lemon","Kiwi","Apple","Mango"]

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