Floating-Point Values

A floating-point value literal must have a decimal point and at least one number after the decimal point.

 
<!DOCTYPE html>
<html>
<head>
    <title>Number Example</title>
    <script type="text/javascript">
          
       var floatNum = 1.2; 
              
       document.writeln(floatNum); 
       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

If there is no digit after the decimal point, the number becomes an integer.

 
<!DOCTYPE html>
<html>
<head>
    <title>Number Example</title>
    <script type="text/javascript">
          
       var floatNum = 1.; 
              
       document.writeln(floatNum); // an integer
       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

If the number being represented is a whole number, it is converted into an integer:

 
<!DOCTYPE html>
<html>
<head>
    <title>Number Example</title>
    <script type="text/javascript">
          
       var floatNum = 1.0; 
              
       document.writeln(floatNum); 
       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

Scientific notation

 
<!DOCTYPE html>
<html>
<head>
    <title>Number Example</title>
    <script type="text/javascript">
          
       var floatNum = 1.234e7; 
              
       document.writeln(floatNum); 
       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

Scientific notation says take 1.234 and multiply it by 10⁷.

 
<!DOCTYPE html>
<html>
<head>
    <title>Number Example</title>
    <script type="text/javascript">
          
       var floatNum = 1.234e-7;
              
       document.writeln(floatNum); 
       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

Scientific notation says take 1.234 and multiply it by 10^-7.