How to Display an Array of Objects in Vanilla JavaScript: Troubleshooting Common Errors

This guide explains how to display an array of objects on your screen with vanilla JavaScript, addressing common issues like the 'Cannot read properties of null' error. Learn step-by-step how to troubleshoot and render your items correctly.
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How to Display an Array of Objects in Vanilla JavaScript: Troubleshooting Common Errors

When you're new to JavaScript, it can be overwhelming, especially when it comes to manipulating the DOM (Document Object Model). One common challenge is displaying an array of objects on the screen upon interaction, such as clicking a button. In this guide, we will discuss a typical issue faced by beginners and provide a clear solution to help you render your items correctly.

The Problem: Uncaught TypeError

You might find yourself trying to display items from a data array, only to encounter an error message like Uncaught TypeError: Cannot read properties of null. This error often occurs when JavaScript is trying to access an element that doesn’t exist in the DOM. Here is a breakdown of the problem you’re facing:

You have an array of objects: This array contains the data you want to display.

You have a button: When you click this button, you want to add a new task and display it on the screen.

You receive an error: The JavaScript engine cannot find the DOM element you're trying to manipulate, resulting in a TypeError.

The Example Code

To illustrate the problem, here is a snippet of your HTML and JavaScript code:

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

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

In this case, your JavaScript is looking for an element with the ID items, but your div only has the class items. This is the core issue leading to the error.

The Solution: Correctly Selecting the Element

To fix this problem and successfully render the items on your screen, you have a couple of options:

Option 1: Add an ID to the Div

The simplest solution would be to modify your HTML to include an id for the div that you want to manipulate. For example:

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

With this change, your JavaScript will be able to correctly find the element:

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

Option 2: Use getElementsByClassName

If you prefer to keep the class instead of adding an id, you can select the div using its class name. Modify your JavaScript as follows:

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

Rendering the Data

Once you have correctly selected the div where you want to display your data, you can proceed to loop through your data array and display each item. Here's how your displayData function should work after addressing the above issues:

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

Final Thoughts

Fixing the Uncaught TypeError can be as simple as ensuring you are referencing the correct element in your DOM. By correctly identifying the elements where you wish to display your data, you not only solve the error but also become more adept at manipulating the DOM with JavaScript. Keep coding, and remember that troubleshooting is part of the learning process!

If you have further questions or need clarification on any points, feel free to leave a comment below!