math.random() in javascript is used to generate random numbers. Its usage syntax is such as "Math.floor(Math.random() * 10 1);". This statement can be used in continuous integers. Get a random number.
The operating environment of this article: windows7 system, javascript version 1.8.5, DELL G3 computer
Use of Math.random() in javascript Detailed explanation
Math.random() I believe everyone knows that this method is used to generate random numbers. However, the general reference manual does not explain how to use this method to generate random numbers within a specified range. This time I will introduce Math.random() in detail and how to use it to generate random numbers within a specified range.
The 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 a continuous integer
Value = Math.floor(Math.random() * the first possible value of the total number of possible values)
Example: Generate random numbers from 1 to 10
The code is as follows:
var rand1 = Math.floor(Math.random() * 10 + 1);
Write a function that generates random numbers from startNumber to endNumber
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);//产生2至8的随机数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
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, it can be written in multiple non-adjacent integers The function
that generates a random value from an integer has the following code:
function selectFromMess() {
return arguments[Math.floor(Math.random() * arguments.length)]
}
//随机产生1、6、8中的一个数
var rand4 = selectFromMess(1, 6, 8);
//也可随机产生文本
var randomTxt1 = selectFromMess("安慰奖", "二等奖", "一等奖");It is troublesome to enter so many parameters every time. You can rewrite the function
and 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 do not change the original method, you can use the apply() method to pass array parameters
Copy the code as follows:
var randTxt3 = selectFromMess.apply(null,arrayTxt);
Recommended study: "javascript basic tutorial》
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