How to Execute a Javascript Function When I Have Its Name as a String

As a JavaScript developer, you may come across situations where you need to execute a JavaScript function when you only have its name as a string. This can be a common requirement when working with dynamic code or when dealing with user input. In this article, we will explore multiple solutions to this problem.

Solution 1: Using the window Object

One way to execute a JavaScript function when you have its name as a string is by using the window object. The window object in JavaScript represents the global window in which all variables, functions, and objects are defined.

Here’s an example of how you can execute a function using the window object:

function greet() {
  console.log("Hello, world!");
}

const functionName = "greet";
window[functionName](); // Output: Hello, world!

Solution 2: Using the eval() Function

Another approach is to use the eval() function, which evaluates JavaScript code represented as a string. While eval() can be a powerful tool, it should be used with caution as it can execute any JavaScript code, including potentially harmful code.

Here’s an example of how you can execute a function using the eval() function:

function greet() {
  console.log("Hello, world!");
}

const functionName = "greet";
eval(functionName + "()"); // Output: Hello, world!

Solution 3: Using the Function Constructor

The Function constructor in JavaScript can also be used to execute a function when you have its name as a string. The Function constructor creates a new function object from a string containing JavaScript code.

Here’s an example of how you can execute a function using the Function constructor:

function greet() {
  console.log("Hello, world!");
}

const functionName = "greet";
const functionToExecute = new Function(functionName);
functionToExecute(); // Output: Hello, world!

These are three different solutions to execute a JavaScript function when you only have its name as a string. Choose the solution that best fits your specific use case and be mindful of the potential risks associated with using the eval() function.

Happy coding!