Multiple validation rules on html form

Question

I have an html form that resembles the following code. My problem is I want to validate based on multiple criteria... a number can either be 0 OR it must be greater than 700. I'm using an array for the input names which is making it tough for me to get a javascript solution working. How would one go about validating in this case with the multiple critera?

<form name="endingweights" method="post">
<input type="hidden" value="1" name="strain[]"></td><td><input type="number" step="any" name="ending[]" min="0" max="1500" required />
<input type="hidden" value="2" name="strain[]"></td><td><input type="number" step="any" name="ending[]" min="0" max="1500" required />
<input type="hidden" value="3" name="strain[]"></td><td><input type="number" step="any" name="ending[]" min="0" max="1500" required />

Answer 1

Got it to validate with the following javascript function.

<script>
function validateForm() {
var x = document.forms["endingweights"].elements["ending[]"];
for (var i = 0; i < x.length; i++) {
var aControl = x[i].value;
if (aControl>0 && aControl<700) {
    alert("Incorrect Weight, must be 0 or greater than 700.");
    x[i].focus();
    return false;
    }
}}
</script>

Answer 2

If you assign id to your inputs, you'll be able to validate via javascript easier. That way you can check the value of the input when the form is submitted.

HTML:

<form name="endingweights" method="post">

    <!-- hidden inputs -->
    <input id="foo" type="number" min="0" max="1500" required>
    <input id="bar" type="number" min="0" max="1500" required>
    <input id="baz" type="number" min="0" max="1500" required>
    <input type="submit" value="Submit">
</form>

JS:

var form = document.forms['endingweights'],
    foo  = document.getElementById('foo'),
    bar  = document.getElementById('bar'),
    baz  = document.getElementById('baz');

// validate inputs and form
form.addEventListener('submit', function(ev) {

    // stop this from auto submitting
    ev.preventDefault();
    ev.stopPropagation();        

    // make sure constraints are followed
    if ((foo.value !== 0 && foo.value <= 700) ||
        (bar.value !== 0 && bar.value <= 700) ||
        (baz.value !== 0 && baz.value <= 700))
    {
        alert("All input values must be either 0 or greater than 700");
        return false;
    }

    // perform other validations if necessary

    // submit form
    form.submit();

}, false);

A demo jsfiddle !

The name attribute is most useful on the server side when handling the submitted data, but id works best when dealing with client-side validation.