Below is the example of the eval() function.

• Example:
  
  

  
  
  

  <script>     // JavaScript to illustrate eval() function     function func() {            // Original string         var a = 4;         var b = 4;            // Finding the multiplication         var value = eval(new String(a * b));         document.write(value);     } // Driver code func(); </script>

• Output:

  16

The eval() function is used to evaluates the expression. If the argument represents one or more JavaScript statements, eval() evaluates the statements. We do not call eval() to evaluate an arithmetic expression.JavaScript evaluates arithmetic expressions automatically.

Syntax:

eval(string)

Parameters: This function accept a single parameter as mentioned above and described below:

• String: A string representing a JavaScript expression, statement, or sequence of statements. The expression can include variables and properties of existing objects.

Return Value: The completion value of evaluating the given code is returned by using eval(). If the completion value is empty, undefined is returned.

Below examples illustrate the eval() function in JavaScript:

Example 1:

Input : eval(new String('2 + 2'));
Output: returns a String object containing "2 + 2"

Input : eval(new String('4 + 4'));
Output: returns a String object containing "4 + 4"

More example codes for the above function are as follows:
Program 1:

Output:

4

Program 2:

Output:

NaN

Supported Browsers:

• Google Chrome
• Internet Explorer
• Mozilla Firefox
• Safari
• Opera