There is more than one way to determine this:
Check the length of the JQuery wrapped set that queries for only checked checkboxes and see if it is 1:
if($("input[name='Check_0']:checked").length === 1)
Check the checked property of the DOM element itself (which is what I'm showing below) for false. To extract the DOM element from the JQuery wrapped set, you can pass an index to the wrapped set ([0] in this case), which extracts just that one item as a DOM element and then you can use the standard DOM API.
if(!$("input[type='checkbox']")[0].checked)
NOTE: It's important to understand that all client-side validation can be easily bypassed by anyone who really wants to. As such, you
should always do a second round of validation on the server that will
be receiving the data.
FYI: You have some invalid HTML: There is no closing tag for input elements and for label elements, you must either nest the element that the label is "for" inside of the label or you must add the for attribute to the label and give it a value of the id of the element that the label is "for". I've corrected both of these things below:
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form>
<div class="ss-item-required">
<label for="userName">Question: What is your name?</label>
<input type="text" name="userName" id="userName">
</div>
<div class="ss-item-required">
<label for="email">Question: What is your email?</label>
<input type="text" name="email" id="email">
</div>
<div class="ss-item-required">
<label for="address">Question: What is your address?</label>
<textarea name="address" rows="8" cols="75" id="address"></textarea>
</div>
<div class="ss-item-required">
<label for="Check_0">Do you agree to out terms?
<input type="checkbox" name="Check_0">
</label>
</div>
<a href="#" onclick="formcheck(); return false">Submit</a>
</form>
<script>
function formcheck() {
var fields = $(".ss-item-required")
.find("select, textarea, input").serializeArray();
$.each(fields, function(i, field) {
if (!field.value){
alert(field.name + ' is required');
}
});
// Check to see if the input is a checkbox and if it's checked
if(!$("input[type='checkbox']")[0].checked){
alert("You must agree to the terms to continue.");
}
}
</script>
Personally (and I'm far from alone on this), the use of JQuery is way overused in today's world. When it came out, the standard DOM API wasn't as mature as it is now and JQuery made DOM element selection and manipulation very simple. Back then, JQuery was a Godsend.
Today, the DOM API has matured and much of what we use to rely on JQuery to make easy, can be done just as easily without JQuery. This means you don't have to reference the JQuery library at all (faster page loading) and you're code follows standards.
If you're interested, here's your code without JQuery:
<form>
<div class="ss-item-required">
<label for="userName">Question: What is your name?</label>
<input type="text" name="name" id="userName">
</div>
<div class="ss-item-required">
<label for="email">Question: What is your email?</label>
<input type="text" name="email" id="email">
</div>
<div class="ss-item-required">
<label for="address">Question: What is your address?</label>
<textarea name="address" rows="8" cols="75" id="address"></textarea>
</div>
<div class="ss-item-required">
<label for="Check_0">Do you agree to out terms?
<input type="checkbox" name="Check_0">
</label>
</div>
<a href="#" onclick="formcheck(); return false">Submit</a>
</form>
<script>
function formcheck() {
// Get all the required elements into an Array
var fields = [].slice.call(document.querySelectorAll(".ss-item-required > *"));
// Loop over the array:
fields.forEach(function(field) {
// Check for text boxes or textareas that have no value
if ((field.type === "text" || field.nodeName.toLowerCase() === "textarea")
&& !field.value){
alert(field.name + ' is required');
// Then check for checkboxes that aren't checked
} else if(field.type === "checkbox" && !field.checked){
alert("You must agree to the terms to continue.");
}
});
}
</script>
