How to generate random numbers in JS

This time I will show you how to generate random numbers with JS, and what are the precautions for generating random numbers with JS. The following is a practical case, let’s take a look.

var chars = ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'];
function generateMixed(n) {
   var res = "";
   for(var i = 0; i < n ; i ++) {
     var id = Math.ceil(Math.random()*35);
     res += chars[id];
   }
   return res;
}

1.Math.random(); The result is a random number between 0-1 (including 0, excluding 1)

2.Math.floor(num); Parameter num is a numerical value, and the function result is the integer part of num.

3.Math.round(num); The parameter num is a numerical value, and the function result is the integer after num is rounded.

Math: Mathematical object, providing mathematical calculations on data.

Math.random(); Returns a random number between 0 and 1 (including 0, excluding 1).

Math.ceil(n); Returns the smallest integer greater than or equal to n.

When using Math.ceil(Math.random()*10);, you mainly get random integers from 1 to 10, and the probability of getting 0 is very small.

Math.round(n); Returns the value of n after rounding.

Use Math.round(Math.random()); to obtain a balanced random integer from 0 to 1.

When using Math.round(Math.random()*10);, you can obtain random integers from 0 to 10 in a basically balanced manner, and the probability of obtaining the minimum value 0 and the maximum value 10 is less than half.

Math.floor(n); Returns the largest integer less than or equal to n.

When using Math.floor(Math.random()*10);, random integers from 0 to 9 can be obtained evenly.
Random example of random function for js to generate random numbers

JavaScript Math.random() built-in function

random函数返回值 
返回0和1之间的伪随机数，可能为0，但总是小于1，[0,1) 
random函数示例 
//返回随机数 
document.write(Math.random()); 
//返回10-20的随机数 
document.write(Math.random()*(20-10)+10); 
//返回指定范围的随机数(m-n之间)的公式 
document.write(Math.random()*(n-m)+m);

Based on time, it can also be The code to generate a random number

is as follows:

var now=new Date(); 
var number = now.getSeconds(); //这将产生一个基于目前时间的0到59的整数。 
var now=new Date(); 
var number = now.getSeconds()%43; //这将产生一个基于目前时间的0到42的整数。

Js The code to generate a 6-digit random number

is as follows:

<script type="text/javascript"> 
function MathRand() 
{ 
var Num=""; 
for(var i=0;i<6;i++) 
{ 
Num+=Math.floor(Math.random()*10); 
} 
document.getElementById("Lb_Random").innerText=Num; 
document.getElementById("Lb_Random").innerHTML=Num; 
} 
</script>

Multiple ways to generate random strings with JS

The code is as follows:

<script language="javascript"> 
function randomString(len) {
　　len = len || 32;
　　var $chars = 'ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz2345678';  /****默认去掉了容易混淆的字符oOLl,9gq,Vv,Uu,I1****/
　　var maxPos = $chars.length;
　　var pwd = '';
　　for (i = 0; i < len; i++) {
　　　　pwd += $chars.charAt(Math.floor(Math.random() * maxPos));
　　}
　　return pwd;
}
document.write(randomString(32));
</script>

It goes without saying how to use it, Call the randomString method, and the parameter len is the length of the returned random string.

The parameter passed is the length. If there is no parameter, the default output is 32 characters.

Several uses of JS to generate random numbers!

The code is as follows:

<script>  
function GetRandomNum(Min,Max)
{  
var Range = Max - Min;  
var Rand = Math.random();  
return(Min + Math.round(Rand * Range));  
}  
var num = GetRandomNum(1,10);  
alert(num);  
</script> 
var chars = ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'];
function generateMixed(n) {
   var res = "";
   for(var i = 0; i < n ; i ++) {
     var id = Math.ceil(Math.random()*35);
     res += chars[id];
   }
   return res;
}

1.Math.random(); The result is a random number between 0-1 (including 0, excluding 1)
2.Math.floor(num); The parameter num is a numerical value, and the function result is the integer part of num.
3.Math.round(num); The parameter num is a numerical value, and the function result is the integer after num is rounded.

Math: Mathematical object, providing mathematical calculations on data.
Math.random(); Returns a random number between 0 and 1 (including 0, excluding 1).

Math.ceil(n); Returns the smallest integer greater than or equal to n.
When using Math.ceil(Math.random()*10);, you mainly get random integers from 1 to 10, and the probability of getting 0 is very small.

Math.round(n); Returns the value of n after rounding.
Use Math.round(Math.random()); to obtain a random integer from 0 to 1 evenly.
When using Math.round(Math.random()*10);, random integers from 0 to 10 can be obtained in a basically balanced manner, and the probability of obtaining the minimum value 0 and the maximum value 10 is less than half.

Math.floor(n); Returns the largest integer less than or equal to n.
When using Math.floor(Math.random()*10);, random integers from 0 to 9 can be obtained evenly.

js generates a random string timestamp to obtain

The default JS generated is 13 digits, which needs to be passed to php/1000

The code is as follows:

timestamp = timestamp/1000;
<script type="text/javascript">
function randomChar(l) {
var x="0123456789qwertyuioplkjhgfdsazxcvbnm";
var tmp="";
var timestamp = new Date().getTime();
for(var i=0;i< l;i++) {
tmp += x.charAt(Math.ceil(Math.random()*100000000)%x.length);
}
return timestamp+tmp;

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

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