JavaScript math.random () using the detailed _javascript tips

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

1. Get a random number in a continuous integer

Value = Math.floor (Math.random () * Total number of possible values + first possible value)
Example: A random number that produces 1-10

Copy Code code as follows:

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

Write a function that produces startnumber to endnumber random numbers

Copy Code code as follows:

function Selectfrom (Startnumber, Endnumber) {
var choice = Endnumber-startnumber + 1;
Return Math.floor (Math.random () * Choice + startnumber)
}
var rand2 = Selectfrom (2,8);//generating random numbers from 2 to 8

2. Get a random number in a nonadjacent integer

2.1 Obtains a random number in the nonadjacent two integers

Example: randomly generating a number in 2 or 4

Copy Code code as follows:

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

2.2 Generating a random number in nonadjacent multiple integers

A function that combines a function parameter array to produce a random value in a nonadjacent number of integers

Copy Code code as follows:

function selectfrommess () {
Return Arguments[math.floor (Math.random () * arguments.length)]
}
Randomly generate a number in 1, 6, 8
var rand4 = selectfrommess (1, 6, 8);
Text can also be generated randomly
var randomTxt1 = selectfrommess ("Consolation Prize", "Second Prize", "First Prize");

Each time you want to enter so many parameters more trouble, you can rewrite the function

Copy Code code as follows:

function Selectfrommessarray (arr) {
Return Arr[math.floor (Math.random () * arr.length)]
}
var arraytxt=["One", "two", "three", "four", "five"];
var randTxt2 = Selectfrommessarray (arraytxt);

Or do not change the original method, you can use the Apply () method to pass the array parameters

Copy Code code as follows:

var randTxt3 = selectfrommess.apply (null,arraytxt);

The use of the Apply method can be seen http://www.jb51.net/article/42705.htm

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