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js generates instance code for the specified range of the random number of

  • 2021-07-02 23:09:00
  • OfStack

1. Randomly generate 4-digit random numbers 


<script language="javascript">
/**
*  Random generation 4 Random number of bits 
* http://www.yulu.ofstack.com
*/
document.write(parseInt(10*Math.random()));  　 // Output 0 ~ 10 Random integer between 
document.write(Math.floor(Math.random()*10+1));  　 // Output 1 ~ 10 Random integer between 
function RndNum(n){
 var rnd="";
 for(var i=0;i<n;i++)
   rnd+=Math.floor(Math.random()*10);
 return rnd;
}
document.write(RndNum(4));  　  　  // A random integer that outputs a random number of specified digits 
</script>

2. Randomly generate random numbers in the specified data range

1), starting from 1 to any value

parseInt (Math. random () * Upper Limit +1);

2), starting from any value to any value 


<script>
parseInt(Math.random()*( Upper limit - Lower limit +1)+ Lower limit ); 
function fRandomBy(under, over){ 
  switch(arguments.length){ 
   case 1: return parseInt(Math.random()*under+1); 
   case 2: return parseInt(Math.random()*(over-under+1) + under); 
   default: return 0; 
  } 
} 
document.write(fRandomBy(1,100)); 　　 // A random integer that outputs random numbers in a specified range 
</script>

// Give a given text box different values according to rules [extension] 
<script>
window.onload=function(){ 
  var o=document.getElementsByTagName('input'); 
  o[0].value=fRandomBy(1,10); 
  o[1].value=fRandomBy(11,20); 
  o[2].value=fRandomBy(1,100); 
  o[3].value=fRandomBy(51,100); 
}
</script>
1-10: <input type="text" /><br /> 
11-20: <input type="text" /><br /> 
1-100: <input type="text" /><br /> 
51-100: <input type="text" /><br />

3. Extension example: 


<html>
<head>
<title>Math- An example of generating random numbers -www.ofstack.com</title>
</head>
<body>
<script language="javascript" type="text/javascript">
total = 0
for(i=1;i<=5000;i++){
  num=Math.random();
  total +=num
}
average = total/5000;
average = Math.round(average*1000)/1000;
document.write("<h1> Average: "+average+"</h1>")
</script>
</body>
</html>
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