How to Set Image src Based on Form Input in JavaScript

Discover how to dynamically display images in HTML using JavaScript by updating the `src` attribute based on form input. It’s easier than you think!
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Dynamically Display Images Based on Form Input with JavaScript

Have you ever wanted to display an image based on user input in an HTML form? Imagine a scenario in which a user enters an ID, and an image corresponding to that ID appears on the page. This can be a common requirement in web applications, yet the process can be confusing if not implemented correctly. In this guide, we’ll uncover how to solve a specific problem related to setting the src of an image based on form input in JavaScript.

The Problem

A user has constructed a basic HTML form with an input field for an ID, but they are finding an issue where the image is not updating as expected. Instead of the selected image appearing, their code is returning a blank string when they try to console log the ID from the input.

HTML Structure

Here’s an overview of the original HTML structure:

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

Initial JavaScript Code

The user's attempt to set the image src included the following JavaScript function:

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

The Key Error

The problem lies in the line:

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

Here, the user mistakenly attempts to access an undefined img property on the image element. In reality, you should directly set the src property of the image element itself.

The Solution: Correcting the Code

Now let’s correct the code step-by-step to make it function as intended. First, we need to adjust how we reference the image element's src property.

Correct JavaScript Function

Here's the revised version of the set_image_path function:

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

Updated HTML Structure

Make sure your HTML looks like this after adding a submit button:

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

Explanation of the Solution

Getting Form Input: The function retrieves the ID value from the input field.

Setting Image Source: It then constructs the path to the image using the ID and assigns this path to the src property of the image element.

Event Handling: An event listener is added to the form to prevent default submissions and to call our function, ensuring the image updates dynamically when the submit button is pressed.

Initial Call: The function is also called when the page loads to display an image if there’s a default input present.

Conclusion

By following these steps, you’ll be able to dynamically change the image displayed on your web page based on user input. This technique enhances the interactivity of your web pages and can be applied in various contexts, from e-commerce sites to portfolio showcases. Happy coding!