Home > Article > Web Front-end > What is the usage of math.random() in javascript
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》
The above is the detailed content of What is the usage of math.random() in javascript. For more information, please follow other related articles on the PHP Chinese website!