preventDefault() stops form validation

Question

having a problem with browser form validation using .preventDefault()

Is there a way to let browser check validation of required inputs, but stops submit?

Is there any flags I can use to get if form is valid?

Thanks

update: using both backbone and jquery

events: {
    "click #commentFormSubmit": "commentFormSubmit",
},
commentFormSubmit: function(el){
    el.preventDefault();
    var $el = $(el.target).parent();

    // this.$el.find('button').prop('disabled', true).addClass('disabled');
    var commentData = {};
    commentData.name = this.$el.find('input[name=comment_name]').val();
    commentData.country = this.$el.find('input[name=comment_country]').val();
    commentData.email = this.$el.find('input[name=comment_email]').val();
    commentData.comment = this.$el.find('textarea[name=comment_text]').val();
    commentData.grade = this.$el.find('.commnt_grade:checked').val();
    console.log('dd')
    this.model.onSubmitComment(commentData);
},

and the form:

    <form action="" class="" method="post">
        <span>
            <input type="text" name="comment_name" class="comment_input" placeholder="{{ 'your name'|_ }}" required>
            <input type="text" name="comment_country" class="comment_input" placeholder="{{ 'country'|_ }}">
            <input type="text" name="comment_email" class="comment_input" placeholder="{{ 'your email'|_ }}" required>
        </span>

        <textarea name="comment_text" id="comment_text" cols="30" rows="10" placeholder="{{ 'your comment'|_ }}" required></textarea>
        <span class="grades">

            <input type="radio" name="commnt_grade" class="commnt_grade" id="grade_1" value="1">
            <label for="grade_1" class="selectGrades" data-eq="1"></label>

            <input type="radio" name="commnt_grade" class="commnt_grade" id="grade_2" value="2">
            <label for="grade_2" class="selectGrades" data-eq="2"></label>

            <input type="radio" name="commnt_grade" class="commnt_grade" id="grade_3" value="3">
            <label for="grade_3" class="selectGrades" data-eq="3"></label>

            <input type="radio" name="commnt_grade" class="commnt_grade" id="grade_4" value="4">
            <label for="grade_4" class="selectGrades" data-eq="4"></label>

            <input type="radio" name="commnt_grade" class="commnt_grade" id="grade_5" value="5">
            <label for="grade_5" class="selectGrades" data-eq="5"></label>
        </span>
        <button type="submit" id="commentFormSubmit">{{ 'submit'|_ }}</button>

    </form>

Answer 1

If you want to validate without submitting, you can get the browser to check the validity of the form by calling checkValidity on it, and to report the validity by calling reportValidity. (On browsers that support HTML validation.)

Calling both checks and then reports, without submitting:

yourFormElement.checkValidity();
yourFormElement.reportValidity();

Example:

$("input[type=button]").on("click", function() {
  var yourFormElement = $("form")[0];
  yourFormElement.checkValidity();
  yourFormElement.reportValidity();
});

<form>
<input type="text" required>
<br><input type="text" required>
<br><input type="button" value="Click to check">
</form>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

You can also do it at the individual element level:

yourInputElement.checkValidity();
yourInputElement.reportValidity();

Example:

$("input[type=button]").on("click", function() {
  var yourInputElement = $("#second")[0];
  yourInputElement.checkValidity();
  yourInputElement.reportValidity();
});

<form>
<input id="first" type="text" required>
<br><input id="second" type="text" required>
<br><input type="button" value="Click to check second field only">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Since you've mentioned you're using jQuery, I'll just emphasize that these are methods of the DOM element, not the jQuery object. So for instance, if your form has an id and you look it up like this:

var $myForm = $("#the-form");

then you'd use

$myForm[0].checkValidity();
$myForm[0].reportValidity();

not

$myForm.checkValidity();  // Wrong
$myForm.reportValidity(); // Wrong

Or you could give yourself a little plugin for it:

jQuery.fn.checkValidity = function() {
    var el = this[0];
    return el && el.checkValidity();
};
jQuery.fn.reportValidity = function() {
    var el = this[0];
    return el && el.reportValidity();
};

That's in keeping with jQuery's various other "getters" in that it only looks at the first element in the set inside the jQuery object.