Using the JS Math.random () function to generate random digital _javascript techniques between N and M

Summary:

This article explains how to use JS to generate a random number between m, the main purpose is for the later JS generated verification code to prepare.

The Math.random () function returns a pseudo-random number between 0 and 1, possibly 0, but always less than 1,[0,1

Generates an integer that contains n but does not contain m: n-m

The first step is to calculate the value of the m-n, assuming equal to W

Step two math.random () *w

Step three math.random () *w+n

Fourth Step parseint (Math.random () *w+n, 10)

Generates N-M, not containing n but an integer containing M:

The first step is to calculate the value of the m-n, assuming equal to W

Step two math.random () *w

Step three math.random () *w+n

Fourth Step Math.floor (Math.random () *w+n) + 1

Generates N-M, no integers containing N and m:

The first step is to calculate the value of the m-n-2, assuming equal to W

Step two math.random () *w

Step three math.random () *w+n +1

Fourth Step Math.Round (Math.random () *w+n+1) or Math.ceil (Math.random () *w+n+1)

Generates N-M, containing the random number of N and M:

The first step is to calculate the value of the m-n, assuming equal to W

Step two math.random () *w

Step three math.random () *w+n

Fourth Step Math.Round (Math.random () *w+n) or Math.ceil (Math.random () *w+n)

Example:

Generates a random integer of 800-1500 that contains 800 but does not contain 1500

Copy Code code as follows:

1500-800 = 700
Math.random () *700
var num = math.random () *700 + 800;
num = parseint (num, 10);

It only takes a simple four steps to complete.

Add:

Math.ceil () returns the smallest integer (rounded function) greater than or equal to the numeric argument, rounding the number

Math.floor () returns the largest integer less than or equal to a numeric parameter, rounding the number

Math.Round () returns the nearest integer to the number, rounded