Using HTML Form Validation without a Form (Kinda)

This will be a quick one. I’ve been a huge fan of HTML-based form validation for some time now. Even though it is far from perfect (and must always be coupled with server-side validation), I love the fact that it can catch errors early in the submission process and create a better experience for users. My first experience with server-side programming was writing Perl scripts to handle forms so anything that improves the process is pretty freaking important to me.

While thinking about another demo I wanted to write (and I sure as hell hope I wrote it down in Trello because I’m drawing a blank on it now) I realized that I’d need to validate some email addresses. While I was fine with a “not perfect” solution, I was curious if there was some way to tie into the browser’s email validation when using:

<input type="email" name="forUsToSpamYou" required />

Basically, I wanted the exact same validation as the field provides, but without using user input and a real form. Turns out you can, and it’s rather easy, but you still have to use a form.

First, I added a field, and then hid it with CSS, because CSS is awesome like that:

<input type="email" id="testEmail">

<style>
#testEmail {
  display: none;
}
</style>

I then create a set of data. This is hard coded, but imagine it comes from some other process.

let tests = [
  "[e-mail]",
  "foo",
  "[e-mail]",
  "zoo"
];

Then to test these values, I just got a reference to the field, set the value, and ran checkValiditity on it:

let emailField = document.querySelector("#testEmail");

tests.forEach(t => {
  emailField.value = t;
  console.log(t, emailField.checkValidity());
});

According to MDN, checkValidity does this: “Returns true if the element’s value has no validity problems; false otherwise. If the element is invalid, this method also causes an invalid event at the element.”

And here is the result, modified to write out results to a div tag:

To be clear, this is not meant to be perfect email validation. Every time I blog about anything related to the topic, folks point out the 500 edge cases that break it. Again, I’m just looking for something to do more of a “soft” validation on the input. And as I said, I was curious if I could “chain” into the HTML logic without using a real (visible) form. Has anyone used anything like this in production? Let me know in a comment please!

Round Two!

I wrote this blog post last night, but didn't actually promote it online. I was planning on doing that today. But after I posted, all around smart guy Šime Vidas posted a great tip in the comments below. I keep forgetting you can create HTML elements in JavaScript. He modified my code such that there is no HTML form field and no CSS required and you simply create the field in JavaScript like so:

let emailField = document.createElement('input');
emailField.type = 'email';

Here's his CodePen: