How to Use jQuery for Input Validation Against Existing Span Values

Learn how to leverage `jQuery` to check if the input value is equal to a value in the span and effectively manage duplicates.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How can JQuery know if the value inside the input is equal to the value inside the span with which it was created and the duplicate value is deleted

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Use jQuery for Input Validation Against Existing Span Values

In web development, managing user inputs and ensuring a smooth experience can sometimes be tricky. One common scenario is needing to check if the value typed into an input box matches any values already displayed on the page, in this case, within a <span>. This guide will show you how to utilize jQuery for this purpose, including how to handle duplicate values.

The Problem: Validate Input Against Span Values

Imagine you have an input field where users can enter tags, and you want to ensure no duplicate tags appear. You might want the input value to be compared against existing values displayed in <span> elements. If a user enters a value that already exists, you should prevent adding it again.

HTML Structure

Here’s the basic HTML structure for your tags input:

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

The Solution: jQuery Implementation

Step 1: Set up the Event Listener

We first need an event listener to respond when the user types in the input box. We’ll listen for the keyup event, which will trigger a function each time the user releases a key.

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

Step 2: Handling Comma Press for Tag Creation

Next, we check if the user has pressed the comma key (with key code 188). If so, we take the input value, remove the last character (comma), and append it as a <span>.

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

Step 3: Comparing Input with Existing Tags

In this step, we need to check if the current input value matches any existing span tags. This is where we previously faced issues. Instead of comparing the input value to a concatenated string of all span texts, we will compare it directly to each span's text.

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

Final Code Example

Here’s the complete jQuery code that integrates all the steps mentioned:

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

Conclusion

By utilizing jQuery, we can effectively manage user inputs in real-time, ensuring that users cannot add duplicate tags. The steps provided should help you build a simple yet effective tag input mechanism that is user-friendly and intuitive.

Next Steps

Feel free to expand on this code by adding more features, such as a notification system for users when they try to add a duplicate tag. Happy coding!