JavaScript | Random

Last Updated : 27 Mar, 2019

The Math.random() function is used to return a floating-point pseudo-random number between range [0,1) , 0 (inclusive) and 1 (exclusive). This random number can be scaled according to the desired range.

Syntax:

Math.random()

Example: This example uses Math.random() function to returns a random number.

<!DOCTYPE html>
<html>
  
<body>
    <h2>Math.random()</h2>
  
    <p>
        Math.random() returns a random
        number between 0 and 1
    </p>
  
    <p id="GFG"></p>
      
    <!-- Script to use Math.random() function -->
    <script>
        document.getElementById("GFG").innerHTML
                = Math.random();
    </script>
</body>
  
</html>                    

Output:

Random Integers: The Math.random() method is used with Math.floor() function to return random integers.

Example:

<!DOCTYPE html>
<html>
  
<body>
    <center>
        <p>
            Math.floor(Math.random() * 11) returns
            a random integer between 0 and 10 
            (inclusive):
        </p>
              
        <p id="demo"></p>
    </center>
      
    <!-- Script to use Math.random() function
    and Math.floor() function to return random
    integer -->
    <script>
        document.getElementById("demo").innerHTML =
                    Math.floor(Math.random() * 11);
    </script>
</body>
  
</html>                    

Output:

Proper Random Function: JavaScript function always returns a random number between min and max where min is inclusive and max may be inclusive or exclusive both.
Example:

<!DOCTYPE html>
<html>
  
<body>
    <p>
        When you click the button it will
        give a random value between 0 and
        9 both inclusive:
    </p>
          
    <button onclick="document.getElementById('GFG').innerHTML = 
                getRndInteger(0, 10)">Try it</button>
                      
    <p id="GFG"></p>
      
    <!-- Script to return random number between
        0 and 10 -->
    <script>
        function getRndInteger(min, max) {
            return Math.floor(Math.random() * (max - min)) + min;
        }
    </script>
</body>
  
</html>                    

Output on first click:

Output on second click:

My Personal Notes

Related Articles