How to Mark the Last Typed Letter if it Doesn't Match a Predefined String in JavaScript and jQuery

Learn how to highlight the last typed letter when it doesn't match a predefined string using JavaScript and jQuery. Make text inputs visually informative with simple coding techniques!
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How to Mark the Last Typed Letter if it Doesn't Match a Predefined String

Typing in a text field can sometimes lead to mistakes, especially when the user needs to match their input to a predefined string. Imagine you're typing "lorex" when the expected input is "lorem." The last letter 'x' doesn’t match, and it can go unnoticed if there’s no visual cue to indicate the error. This guide will walk you through a practical solution to highlight the last typed letter when it doesn't fit the expected string format, using JavaScript and jQuery.

Why is Highlighting Important?

Highlighting the incorrect last typed letter serves as immediate feedback to users, allowing them to recognize and correct their mistakes. This simple visual cue can improve user experience significantly, especially in applications where correct input is crucial, such as forms, search bars, or any data entry tasks.

The Problem

To help illustrate this, let's take the specific scenario where:

The predefined string is lorem.

The user types lorex.

In this situation, we aim to visually mark the 'x', since it does not match the predefined string's end.

JavaScript Error Encountered

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

The error happened because last was a string (the last character), and we attempted to call .css() on it, which led to failure.

The Solution

To solve the problem, we need to create a new HTML structure that will allow us to apply CSS styles to the last erroneous letter. Here’s how you can accomplish this:

Step 1: Create a Span Element

Instead of trying to style a string directly, we will create a <span> element and set its background color in JavaScript. Here’s a concise example:

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

In the code above, we:

Create a <span> element.

Set its background color to orange.

Set its inner text to the last typed letter.

Reassign the text content of the story div to everything except the last letter.

Append the <span> after the story div.

Step 2: Implementation with jQuery

If you prefer jQuery for its simplicity and readability, here's how you can achieve the same effect in a more concise way:

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

In this jQuery example:

We use the .html() method to update the content of the story element by combining the string without the last letter and the highlighted last letter in a <span>.

Conclusion

This method can significantly enhance user experience by providing immediate visual feedback on their input. Highlighting the last incorrect letter ensures users are aware of their mistakes and prompts them to correct them quickly.

By incorporating this feature into your web applications, you’ll make your forms more intuitive, which could lead to higher accuracy in data entry and improved user satisfaction.

Feel free to adapt and expand upon this solution to suit your specific needs! Happy coding!