Manually trigger html5 validation on button click

I've achieved this by doing steps below:

1) I'm having form:

<form>
    <textarea required></textarea>
    <input type="submit" style="display:none;"/>
</form>

<a>Some other button to trigger event</a>

2) Now we have to check if the form is filled correctly:

//this is <a> click event:
if (!$('form')[0].checkValidity()) {
    $('form').find('input[type="submit"]').click();
    return false;
}

This will trigger form sending but won't send because there are errors ;)

It appears that html5 validation errors are displayed on input[type="submit"] click :)

Hope will work for You too! :)

Try

reportValidity()

So you'd have

$("#btn").on("click", function(){
    if($("#the-form")[0].checkValidity()) {
        alert('validated');
    }
    else {
        $("#the-form")[0].reportValidity();
    }
});