search():在字符串中搜索一個值並返回第一個匹配項的位置

將字符串與正則表達式匹配**

返回第一個匹配項的索引（位置）

如果未找到匹配項，則該方法返回 -1

方法區分大小寫

const arr="Mr. Blue has a blue house";
const searchArr=arr.search("Blue")
console.log(searchArr)
//4

charAt():從一個字符串中返回指定的字符

const anyString = "Brave new world";
console.log(anyString.charAt(0))//"B"
console.log(anyString.charAt(1))//"r"
console.log(anyString.charAt(3))//"v"
console.log(anyString.charAt(4))//"e"
console.log(anyString.charAt(5))//"n"
console.log(anyString.charAt(6))//" "
console.log(anyString.charAt(999))//" "

Math.atan2():靜態方法返回平面中正 x 軸與從 (0, 0) 到點 (x, y) 的射線之間的角度（以弧度為單位）

function calcAngleDegrees(x, y) {
  return Math.atan2(y, x) * 180 / Math.PI;
}

console.log(calcAngleDegrees(5, 5));
// Expected output: 45

console.log(calcAngleDegrees(10, 10));
// Expected output: 45

console.log(calcAngleDegrees(0, 10));
// Expected output: 90

Math.acos():返回數字的Math.acos()反餘弦值（以弧度為單位）

// 以弧度計算直角三角形的角度
function calcAngle(adjacent, hypotenuse) {
  return Math.acos(adjacent / hypotenuse);
}

console.log(calcAngle(8, 10));
// Expected output: 0.6435011087932843

console.log(calcAngle(5, 3));
// Expected output: NaN

Math.asin():返回數字的Math.asin()反正弦（以弧度為單位）

// 以弧度計算直角三角形的角度
function calcAngle(opposite, hypotenuse) {
  return Math.asin(opposite / hypotenuse);
}

console.log(calcAngle(6, 10));
// Expected output: 0.6435011087932844

console.log(calcAngle(5, 3));
// Expected output: NaN

Math.max():查詢最大值

var myArray1 = [1, 5, 6, 2, 3];
var max1 = Math.max(...myArray1);
console.log('max1',max1)
//"max1" 6

function MyMax(myarr){
    var al = myarr.length;
    maximum = myarr[al-1];
    while (al--){
        if(myarr[al] > maximum){
            maximum = myarr[al]
        }
    }
    return maximum;
};

var myArray2 = [1, 5, 8, 2, 3];
var max2 = MyMax(myArray2);
console.log('max2',max2)
//"max2" 8

Math.tan():返回以弧度為單位的數字的正切值

function getTanFromDegrees(degrees) {
  return Math.tan(degrees * Math.PI / 180);
}

console.log(getTanFromDegrees(0));
// Expected output: 0

console.log(getTanFromDegrees(45));
// Expected output: 0.9999999999999999

console.log(getTanFromDegrees(90));
// Expected output: 16331239353195370

Math.cos():返回以弧度為單位的數字的餘弦值

function getCircleX(radians, radius) {
  return Math.cos(radians) * radius;
}

console.log(getCircleX(1, 10));
// Expected output: 5.403023058681398

console.log(getCircleX(2, 10));
// Expected output: -4.161468365471424

console.log(getCircleX(Math.PI, 10));
// Expected output: -10

Math.abs():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.abs("-1"); // 1
Math.abs(-2); // 2
Math.abs(null); // 0
Math.abs(""); // 0
Math.abs([]); // 0
Math.abs([2]); // 2
Math.abs([1, 2]); // NaN
Math.abs({}); // NaN
Math.abs("string"); // NaN
Math.abs(); // NaN

Math.atan():// 以弧度計算直角三角形的角度

function calcAngle(opposite, adjacent) {
  return Math.atan(opposite / adjacent);
}


console.log(calcAngle(8, 10));
// Expected output: 0.6747409422235527

console.log(calcAngle(5, 3));
// Expected output: 1.0303768265243125