I have created HTML checkboxes in a JSP loop and I wish to do validation for those checkboxes in JavaScript, how should I do that?

Normally, for a single object, we can do it like window.document.form.checkbox or something similar.

Not sure about checkboxes appearing in loop.

<%   
    for(int i=1; i<somevalue; i++)    //jsp 
    {
%>
    <input type="checkbox"  name="chkbox_"<%=i> value="<%=something%>">   
    <!-- html -->
<%
    }
%>

I have created HTML checkboxes in a JSP loop and I wish to do validation for those checkboxes in JavaScript, how should I do that?

Normally, for a single object, we can do it like window.document.form.checkbox or something similar.

Not sure about checkboxes appearing in loop.

<%   
    for(int i=1; i<somevalue; i++)    //jsp 
    {
%>
    <input type="checkbox"  name="chkbox_"<%=i> value="<%=something%>">   
    <!-- html -->
<%
    }
%>

• javascript
• java

Share Improve this question Follow edited Sep 12, 2024 at 11:49 Mark Schultheiss 34.2k1212 gold badges7272 silver badges113113 bronze badges asked Nov 28, 2014 at 18:19 hadeshades 4,7341010 gold badges5252 silver badges7878 bronze badges

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2 Answers 2

Sorted by: Reset to default 1

According to me, we have some solutions:

1. If you don't want to modify HTML code and using Javascript. You can use this method getElementsByTagName - Example

var checkboxes = document.getElementsByTagName("input");
for (var i = 0; i < checkboxes.length; i++) {
    if (checkboxes[i].type == "checkbox") {
        var isChecked = checkboxes[i].checked;
    }
}

2. Add class attribute for all checkbox and use this method getElementsByClassName

3. Add id attribute for each checkbox and use getElementById method

4. Use JQuery

$("input[type=='checkbox']").each(obj, function(key, value) {
   //   Do something
});

It looks like your loop ends prematurely i.e. < instead of <=, since you are starting at 1. Also, you did not close your name attribute correctly.

Note: You should include your outer <form>.

<form name="checkbox-form">
  <% for (int i = 1; i <= checkboxCount; i++) { %>
    <input type="checkbox" name="chkbox_<%=i%>" value="<%=something%>">   
    <!-- html -->
  <% } %>
</form>

You can query for checkboxes within the form via:

const form = document.forms['checkbox-form'];
const checkboxes = form.querySelectorAll('input[type="checkbox"]');

Alternatively, select them by their name:

const form = document.forms['checkbox-form'];
const checkboxes = form.querySelectorAll('[name^="chkbox_"]');