# Introduction of javascript Number and Math Objects

• 2021-12-05 05:30:37
• OfStack

Directory 1. Number2 in javascript. Math object in Javascript

## 1. Number in javascript

`javascript ` The numeric type belongs to the original type. In addition to the common values we know in decimal, we can also use 0x for 106-ary integers, 0b for binary integers, and 0O for octal integers

``````
0xa // Correspondence 10 Binary system  10

0b101 // Correspondence 10 Binary system  5

0o22  // Correspondence 10 Binary system  18

``````

In `javascript` 0 can be used as a divisor, and the return value is infinity. This is very different from other languages. For example `python` 0 cannot be used as a divisor.

``````
1/0   // Infinity

``````

`Infinity ` Indicates an infinite value

But the result of 0/0 is `NaN` , `NaN ` It is also a numeric type, which is a numeric value of a special number, indicating that it is not a numeric value of a "numeric value".

When converting a non-numeric string to a numeric type, NaN is also returned, for example ` praseInt('a')`

Can be used `Number.isNaN` Or global function `isNaN ` Determine whether a value is `NaN`

``````
Number.isNaN(2)  //false
Number.isNaN('a') // true
Number.isNan('2') //false

``````

Numeric value is a primitive type and also has a corresponding wrapper object `javascript`0 , `Number ` Class provides many methods, including the above-mentioned `isNaN` .

``````
n = new Number(10)
n.valueOf() === 10   //true

``````

The value of the object n defined by the wrapper class is exactly the same as the original type value 10.

## 2. Math object in Javascript

`Math` Object is `Javascript` The global object of, provides many methods of mathematical operation

Math. max Get the maximum value:

``````
let max = Math.max(1,2,3,4)
console.log(max)  //4

``````

Math. min Get the minimum value:

``````
let min = Math.min(1,2,3,4)
console.log(min) //1

``````

If you are looking for the maximum and minimum values in an array, you can use the extension operator... to solve the array into multiple parameter values

``````
Math.max(...[1,2,3,4]) //4

``````

Math. ceil rounding up:

``````
console.log(Math.ceil(2.3)) // 3

``````

Math. floor rounding down:

``````
console.log(Math.floor(2.8)) // 2

``````

Math. round 4 rounded by 5 rounded:

``````
console.log(Math.round(2.5))  //3
console.log(Math.round(2.3))  //2

``````

`Math.random ` Randomly generate 1 floating point number between [0, 1], including 0 but not 1

``````
1/0   // Infinity

``````
0

Randomly generate an integer between 0 and 10

``````
1/0   // Infinity

``````
1

Math. pow power:

``````
1/0   // Infinity

``````
2

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