Detailed explanation of the use of Math.random() in javascript_javascript skills

Math.random() method returns a random number greater than or equal to 0 and less than 1. For some sites, this method is very practical, because it can be used to randomly display some famous quotes and news events.

1. Obtain a random number from continuous integers

Value = Math.floor(Math.random() * total number of possible values ​​first possible value)
Example: Generate random numbers from 1-10

Copy code The code is as follows:

var rand1 = Math.floor(Math.random() * 10 1);

Write a function that generates random numbers from startNumber to endNumber

Copy code The code is as follows:

function selectFrom(startNumber, endNumber) {
var choice = endNumber - startNumber 1;
Return Math.floor(Math.random() * choice startNumber)
}
var rand2 = selectFrom(2,8);//Generate random numbers from 2 to 8

2. Obtain a random number from non-adjacent integers

2.1 Obtain a random number from two non-adjacent integers

Example: Randomly generate a number between 2 or 4

Copy code The code is as follows:

var rand3 = Math.random() < 0.5 ? 2 : 4;

2.2 Generate a random number from multiple non-adjacent integers

Combined with the function parameter array, you can write a function that generates a random value among multiple non-adjacent integers

Copy code The code is as follows:

function selectFromMess() {
Return arguments[Math.floor(Math.random() * arguments.length)]
}
//Randomly generate a number among 1, 6, and 8
var rand4 = selectFromMess(1, 6, 8);
//You can also randomly generate text
var randomTxt1 = selectFromMess("Consolation Prize", "Second Prize", "First Prize");

It is troublesome to enter so many parameters every time. You can rewrite the function

Copy code The code is as follows:

function selectFromMessArray(arr) {
Return arr[Math.floor(Math.random() * arr.length)]
}
var arrayTxt=["一","二","三","四","五"];
var randTxt2 = selectFromMessArray(arrayTxt);

Or without changing the original method, you can use the apply() method to pass array parameters

Copy code The code is as follows:

var randTxt3 = selectFromMess.apply(null,arrayTxt);

For information about the use of the apply method, please see http://www.jb51.net/article/42705.htm

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