JavaScript built-in object Math example sharing

This article brings you relevant knowledge about the javascript built-in object math. It explains the usage of common functions in Math based on examples, including the absolute value method, three rounding methods, etc. Wait, let’s take a look at it together, I hope it will be helpful to everyone.

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Math Overview

The Math object is not a constructor, it has properties and methods for mathematical constants and functions. Math-related operations (finding absolute values, rounding, maximum values, etc.) can use members in Math.

Usage of common functions in Math

• Math.PI //Pi

• ##Math. floor () //Round down

• Math.ceil () //Round up

• Math.round () // Round to the nearest integer. Note - 3.5. The result is -3

##Math.abs () //Absolute value
Math.max ()/ Math.min() //Find the maximum and minimum values ​​

• ##Math.random() //Return a random decimal 0=
1.Absolute value method

 //1.绝对值方法
        console.log(Math.abs(1)); // 1
        console.log(Math.abs(-1));  //1
        console.log(Math.abs('-5')); //5  会隐式转换，将数字字符串转换为数字，然后取绝对值
        console.log(Math.abs('aniu')); // NaN

2.Three rounding Method

//2.三个取整方法
        console.log(Math.floor(1.1)); //1
        console.log(Math.floor(1.9)); //1
        console.log(Math.floor(-1.1)); //-2

        console.log(Math.ceil(1.1));  // 2
        console.log(Math.ceil(1.9)); //2
        console.log(Math.ceil(-1.9)); //-1

        console.log(Math.round(1.5)); //2 四舍五入 .5这个特殊，是往大了取
        console.log(Math.round(-1.5)); // -1  往大了取
        console.log(Math.round(-1.2));  // -1

3. Find the maximum/minimum value

//3.求最大值/最小值
        console.log(Math.max(1,5,78,46));
        console.log(Math.min(1,5,78,46));

4. Random numbers

 //4.随机数
        console.log(Math.random());

Case - A small algorithm to find a random integer between two numbers (important)

Find a random integer between two numbers and contain these two numbers:

//Core algorithm

Math.floor(Math.random()*(max-min)) min;

function getRandom(min,max){
            return Math.floor(Math.random()*(max-min)) + min;
        }

        console.log(getRandom(1,7));

Case-Random Roll Call (Hey hey hey)

//随机点名
  var arr = ['阿牛','梦梦','小鸣人','winter','小何','WA','贱神','扎哇']  //太多啦，就写这些举例啦
  console.log(arr);
  console.log('阿牛爱你们???');
  function getRandom(min,max){
          return Math.floor(Math.random()*(max-min)) + min;
       }

  console.log('随机点中了：' + arr[getRandom(0,arr.length - 1)]);

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