Math.floor():取得最大整數

const mathFloor=Math.floor(1.6);
console.log(mathFloor);
//1

Math.imul(3, 4);//12
Math.imul(-5, 12);//-60

Math.min():查詢最小值

var myArray1 = [1, 5, 6, 2, 3];
var min1 = Math.min(...myArray1);

//console.log(min1),
//1

var myArray2 = [1, 5, 6, 2, 3];
var min2 = Math.min.apply(null, myArray2);
console.log(min2)
//1


function MyMin(myarr){
    var al = myarr.length;
    minimum = myarr[al-1];
    while (al--){
        if(myarr[al] < minimum){
            minimum = myarr[al]
        }
    }
    return minimum;
};
var myArray3 = [1, 5, 6, 2, 3];
var min3 = MyMin(myArray3);
console.log(min3)




      
    

Math.pow():將其參數強制為數字。不可強制值將變為NaN，Math.abs()也使得返回NaN

Math.pow(x,y)=Xy
x:基數
y:指數

console.log(Math.pow(7, 3));
// Expected output: 343

console.log(Math.pow(4, 0.5));
// Expected output: 2

console.log(Math.pow(7, -2));
// Expected output: 0.02040816326530612
//                  (1/49)

console.log(Math.pow(-7, 0.5));
// Expected output: NaN

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"]