JavaScript Number object

Introduction

Number object is a numerical object, including integers, floating point numbers, etc. in js.

Definition

var a = 1;

var b = 1.1;

Attribute

##1 Number.MAX_VALUE: Represents the largest value in JS Number, approximately 1.79e+308

2 Number.MIN_VALUE: Represents the smallest number in JS, approximately 5e-324

3 Number.NaN: Returns NaN, indicating a non-numeric value, Not equal to any other number, including NaN itself. Number.isNaN() should be used to judge.

4 Number.NEGATIVE_INFINITY: Returns -Infinity, indicating negative infinity.

5 Number.POSITIVE_INFINITY: Returns Infinity, indicating positive infinity. If the calculated value is greater than Number.MAX_VALUE, Infinity is returned.

Method

##1 Number.isInteger(value): Determine whether the parameter is an integer

Parameters:

①value {Number}: number

Return value:

{Boolean} Returns whether the parameter is an integer. Pure integer strings also return false.

Example:

Number.isInteger(1); // => true

Number.isInteger(1.1); // => false

Number.isInteger('1'); // => false: Pure integer strings also return false

Number.isInteger('1.1'); // => false

Number.isInteger('a'); // => false: non-string returns false

2 Number.isNaN(value): determines whether the parameter is NaN

parameter :

①value {Object} : Any type

Return value:

{Boolean} Whether the return parameter is NaN.

Example:

Number.isNaN(NaN); // => true

Number.isNaN('NaN'); // => false :' NaN' string is not NaN

Number.isNaN(1); // => false

Number.isNaN('1'); // => false

3 Number.parseFloat(value): Convert the parameter to a floating point number

Parameters:

①value {Number | NumberStr}: Number or pure numeric string

return value:

{Integer | Float} Returns an integer or floating point number

Example:

Number.parseFloat(1); // => 1: Integer or returns an integer

Number.parseFloat(1.1); // => 1.1

Number.parseFloat('1aaa'); // => 1: If the string is preceded by a number, only numbers are returned

Number.parseFloat('1.1aaa'); // => 1.1

Number.parseFloat('a1'); // => NaN: does not start with a number, returns NaN

Number.parseFloat('a'); // => NaN

4 Number.parseInt(value): Convert the parameter to an integer

Parameter:

①value {Number | NumberStr}: Number or pure numeric string

Return value:

{Integer} Return integer value

Example:

Number.parseInt(1); // => 1

Number.parseInt(1.1); // => 1: Floating point number returns integer

Number.parseInt('1aaa' ); // => 1: If the string is preceded by a number, only numbers are returned

Number.parseInt('1.1aaa'); // => 1

Number.parseInt ('a1'); // => NaN: does not start with a number, returns NaN

Number.parseInt('a'); // => NaN

Octal and Hexadecimal

If the prefix is 0, JavaScript will interpret the numeric constant as an octal number. If the prefix is 0 and "x", it will be interpreted as a hexadecimal number. .

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By default, JavaScript numbers are displayed in decimal.

But you can use the toString() method to output hexadecimal, octal, or binary.

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Infinity

When the numerical operation result exceeds the upper limit of the number that JavaScript can represent (overflow), the result is a special infinity value, which is represented by Infinity in JavaScript express. Similarly, when the value of a negative number exceeds the range of negative numbers that JavaScript can represent, the result is negative infinity, which is represented by -Infinity in JavaScript. Infinite values behave as we would expect: operations based on their addition, subtraction, multiplication, and division still result in infinity (while retaining their signs, of course).