The Math.random() JavaScript method returns a floating-point random number between 0 (inclusive) and 1 (not included).
This method can be used to generate random integer numbers in JavaScript.
Bellow there are 3 functions with examples to generate random integer numbers with various criterias.


Examples random numbers in JS

1. The randomNr() function from the following example returns a random integer between a minimum and maximum number.
//Returns a random integer between min (inclusive) and max (inclusive)
function randomNr(min, max){
 return Math.floor(Math.random() * (max - min + 1)) + min;
}

//Test
var nr_al = randomNr(1, 9999);
document.write(nr_al); //78 /355 /7098
2. The randNrDigits() function presented in the following example returns a random integer with a specified number of digits.
//Returns a random integer with a specified number of digits (nd)
function randNrDigits(nd){
 var n0 =1;
 for(var i=1; i<nd; i++) n0 +='0';
 return Math.floor((1*n0) + Math.random() * (9*n0));
}

//Test
var nr_al = randNrDigits(4);
document.write(nr_al); //3424
3. The randNrUniqueDigits() function from the following example returns a random integer with a specified number of digits, and the digits do not repeat.
//Returns a random integer with digits that not repeat, with specified number of digits (nd)
function randNrUniqueDigits(nd){
 var ar_nr =[0,1,2,3,4,5,6,7,8,9];
 for(let i = ar_nr.length -1; i >0; i--){
 let j = Math.floor(Math.random() * (i + 1)); 
 [ar_nr[i], ar_nr[j]] = [ar_nr[j], ar_nr[i]];
 }

 return ar_nr.splice(1, nd).join('')*1;
}

//Test
var nr_al = randNrUniqueDigits(4);
document.write(nr_al); //5940

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Which attribute specifies the HTTP method (GET, POST) used to submit the form-data?
action method value
<form action="script.php" method="post"> ... </form>
Which CSS property allows to add shadow to boxes?
background-image box-shadow border-radius
#id {
  background-color: #bbfeda;
  box-shadow: 11px 11px 5px #7878da;
}
Which function removes the first element from an array?
pop() push() shift()
var fruits = ["apple", "apricot", "banana"];
fruits.shift();
alert(fruits.length);           // 2
Indicate the function that can be used to check if a PHP extension is instaled.
function() filetype() extension_loaded()
if(extension_loaded("PDO") === true) echo "PDO is available."
Generate random numbers in JavaScript

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