动态文本区域的Javascript验证

Question

Hi I'm using a CMS which dynamically creates textareas on product pages of an ecommerce site. The text area has a different ID on each different product page. I am in need of some javascript that will check if all textareas on a page are empty and if so display a warning message. I cant assign an id to the text areas so cant use this script I normally use. Any help is much appreciated!

function validate() {
var val = document.getElementById('textarea').value;
if (/^\s*$/g.test(val)) {
    alert('Wrong content!');
}
} 

Hey Benjamin thanks for your reply, I couldn't get the code working in comments, thinking I'm having a bad day. So as i was trying to say I'm not the greatest at Javascript (but eager to learn!) I've added this to my page but it doesn't appear to work:

<script> 
var areas = document.getElementsByTagName("textarea"); 
// now iterate them for
(var i=0;i<areas.length;i++){ 
 var val = areas[i].value; 
 if (/^\s*$/g.test(val)) { 
 // whatever 
 } 
} </script>

With this as in the body

<div class="description">Further Details <br>
<textarea id="catProdInstructions_6486638" class="productTextarea"></textarea>
</div>

Thanks for your time on this :)

Answer 1

You can use getElementsByTagName to fetch all <textarea> s.

It returns a NodeList of all the text areas currently in the page which you can iterate.

var areas = document.getElementsByTagName("textarea");
// now iterate them
for(var i=0;i<areas.length;i++){
    var val = areas[i].value;
    if (/^\s*$/g.test(val)) {
        // whatever
    }
}

The NodeList returned is live , this means that it'll update itself automatically as new textarea elements are added dynamically even if you fetch them with ajax or create them with code.