JavaScript - The Function() Constructor (Javascript)

The function statement is not the only way to define a new function but also, you can define your function dynamically using Function( ) constructor along with the new operator.
Note: This is the terminology from Object Oriented Programming. You may not feel comfortable for the first time, which is OK.

Syntax:

Following is the syntax to create a function using Function( ) constructor along with the new operator.

<script type="text/javascript"> <!-- var variablename = new Function(Arg1, Arg2..., "Function Body"); //--> </script>

The Function() constructor expects any number of string arguments. The last argument is the body of the function - it can contain arbitrary JavaScript statements, separated from each other by semicolons.
Notice that the Function() constructor is not passed any argument that specifies a name for the function it creates. The unnamed functions created with the Function() constructor are called anonymous functions.

Example:

Here is an example of creating a function in this way:

<script type="text/javascript"> <!-- var func = new Function("x", "y", "return x*y;"); //--> </script>

This line of code creates a new function that is more or less equivalent to a function defined with the familiar syntax:

<script type="text/javascript"> <!-- function f(x, y){ return x*y; } //--> </script>

It means you can call above function as follows:

<script type="text/javascript"> <!-- func(10,20); // This will produce 200 //--> </script>