Solving the Cannot use addEventListener with for in loop Error in JavaScript

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Understanding the addEventListener Error in JavaScript

The Problem

Here’s a quick look at the code that causes the problem:

[[See Video to Reveal this Text or Code Snippet]]

In this code:

Two buttons are selected as firstBtn and secondBtn.

An object data is created, holding information about each button.

The for...in loop tries to add an event listener to each button.

The error arises because key in the loop is a string (the name of the property in the data object) and not the actual button element that you want to attach the event listener to.

The Solution

To successfully attach event listeners to your buttons, you need to modify your approach. Below is a revised version of the code that achieves the desired functionality:

Step 1: Store Elements in an Array

Instead of using just keys in an object, we can store both the button elements and their respective messages in an array of objects. This allows for easier looping through the elements and their messages.

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Use a Simple Loop

Next, we can use a for...of loop to go through each object in the array, allowing us to directly access the button element and its message.

[[See Video to Reveal this Text or Code Snippet]]

Complete Code Example

Here’s how the complete and corrected example looks:

[[See Video to Reveal this Text or Code Snippet]]

And here’s the corresponding HTML for the buttons:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By restructuring your data to include both the DOM elements and the associated messages, and using a for...of loop, you can efficiently manage event listeners without running into the common addEventListener issues. This not only makes your code cleaner but also reduces redundancy— a best practice in programming. Happy coding!