JavaScript Function() Constructor

Last Updated : 03 Feb, 2023

The Javascript Function Constructor is used to create a new function object using the Function() constructor with the new operator. The Javascript Function Constructor creates a function that has a global scope.

Syntax:

var variable = new Function(arg1, arg2..., Function Body)

Parameters:

arg*: It is an optional parameter. A function can contain any number of string arguments.
Function Body: It is an argument that contains the Javascript statements containing the function definition.

Below are some examples that show the use of the Javascript function constructor.

Example 1: In this example, we will see the basic use of the Javascript function constructor.

HTML

<!DOCTYPE HTML> 
<html> 
<head> 
    <script type="text/javascript"> 
        <!-- 
        var func = new Function("x", "y", "return x*y;"); 
        function geeks() { 
           var result; 
           result = func(10,20); 
           document.write ( result ); 
        } 
    </script> 
</head> 
  
<body> 
    <h1 style="color:green"> 
        Geeks For Geeks 
    </h1> 
    <h3>Javascript function constructor</h3> 
    <p>Click the following button to see the result</p> 
  
    <input type="button" onclick="geeks()"value="Click Me"> 
  
</body> 
</html>

Output:

Javascript function constructor

Example 2: In this example, we will create a Javascript constructor and print the values of the function.

HTML

<!DOCTYPE HTML> 
<html> 
<head> 
    <script type="text/javascript"> 
        <!-- 
        var func = new Function("firstName", "lastName",  
                                "return firstName + ' ' + lastName + ' ' + firstName;"); 
        function geeks() { 
           var result; 
           result = func("Geeks","for"); 
           document.write ( result ); 
        } 
    </script> 
</head> 
  
<body> 
    <h1 style="color:green"> 
        Geeks For Geeks 
    </h1> 
    <h3>Javascript function constructor</h3> 
    <p>Click the following button to see the result</p> 
  
    <input type="button" onclick="geeks()"value="Click Me"> 
  
</body> 
</html>