How to Efficiently Pass Values from HTML Forms to JavaScript

Discover a simple method to pass user inputs from an HTML number field to a JavaScript function without jQuery. Perfect for validating BSN numbers!
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This video is based on the question https://stackoverflow.com/q/74753320/ asked by the user 'Freddy Meijer' ( https://stackoverflow.com/u/15101206/ ) and on the answer https://stackoverflow.com/a/74753424/ provided by the user 'Ivan Beliakov' ( https://stackoverflow.com/u/13304024/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Efficiently Pass Values from HTML Forms to JavaScript

If you've ever tried to integrate a number field from an HTML form with a JavaScript function, you might have encountered a bit of confusion, especially if you're not familiar with using libraries like jQuery. In this post, we'll break down the steps to pass the value of a number field from your web page to a JavaScript function seamlessly. This guide is especially useful for tasks such as validating a BSN (Social Security Number) — a validation that requires a bit of calculation based on user input.

Understanding the Problem

You've set up a web application where users can input a nine-digit number to check if it is a valid BSN number. When the user clicks a button, you need to trigger a JavaScript function that processes the inputted number and returns either a success or failure message. Initially, you may have faced issues with passing user input from the HTML form to the JavaScript function, which is quite a common challenge.

Here's an overview of our setup:

HTML Form: Where users input the number.

Button: When clicked, should run the JavaScript validation function.

JavaScript Function: Validates the nine-digit number based on the '11-test' calculation.

Let's Solve It

Step 1: Selecting the Number Input

Instead of using jQuery to retrieve the value from the input field, we can use Vanilla JavaScript.

You can do that easily with:

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

This line of code selects your input field by its ID, allowing you to access the value entered by the user.

Step 2: Calling the JavaScript Function with User Input

Once you have the input value stored in numberInput, you can call your validation function (bsn_check) using that input as follows:

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

This passes the value directly to your function, allowing it to process the number for validation.

Alternative Approach: Inline HTML Event Handler

If you want to simplify your code even more, you can handle everything directly within the HTML. Here's how you can modify your button:

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

This code does two things:

Captures the event when the button is clicked.

Retrieves the value from the input field and passes it directly to the bsn_check function, updating the content of the paragraph with the ID bsn based on the function's return message.

Conclusion

By using Vanilla JavaScript, you can effectively simplify the process of retrieving and utilizing user input from an HTML form. No jQuery needed! The key points include selecting the input element correctly and ensuring that the function call receives the appropriate value.

Now you can easily validate BSN numbers with user inputs on your website. Enjoy coding, and don't hesitate to explore more JavaScript functionalities to enhance your web applications!

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