CODEWITHSUNDEEP
javascript
Mark Kadlec
Mark Kadlec

Reputation: 8450

Javascript to check whether a checkbox is being checked or unchecked

I have a javascript routine that is performing actions on a group of checkboxes, but the final action I want to set the clicked checkbox to checked or unchecked based on if the user was checking the box or unchecking.

Unfortunately, every time I check for whether it is being checked or unchecked, it returns "on" indicating the user is always checking the box! Any help would be appreciated, I've also included the javascript.

// Uncheck all the checkboxs with the same Tax Credit
for (i=0; i<arrChecks.length; i++)
{
    var attribute = arrChecks[i].getAttribute("xid")
    if (attribute == elementName)
    {
        // if the current state is checked, unchecked and vice-versa
        if (arrChecks[i].value == "on")   // <-- This is always returning true, even if the box is being unchecked
        {
            arrChecks[i].checked = 1;
        } else {
            arrChecks[i].checked = 0;
        }

    } else {
        arrChecks[i].checked = 0;
    }
}

Upvotes: 30

Views: 248219

Answers (7)

shanti gola
shanti gola

Reputation: 51

function enter_comment(super_id) {
    if (!(document.getElementById(super_id).checked)) {
        alert('selected checkbox is unchecked now')
    } else {
        alert('selected checkbox is checked now');
    }
}

<input type="checkbox" name="a" id="1" value="1" onclick="enter_comment(this.value)" />

<input type="checkbox" name="b" id="2" value="2" onclick="enter_comment(this.value)" />

Upvotes: 5

Suresh
Suresh

Reputation: 31

function CHeck(){
    var ChkBox = document.getElementById("CheckBox1");
    alert(ChkBox.Checked);
}

<asp:CheckBox ID="CheckBox1" runat="server" onclick="CHeck()" />

Upvotes: 3

Paolo Bergantino
Paolo Bergantino

Reputation: 488414

The value attribute of a checkbox is what you set by:

<input type='checkbox' name='test' value='1'>

So when someone checks that box, the server receives a variable named test with a value of 1 - what you want to check for is not the value of it (which will never change, whether it is checked or not) but the checked status of the checkbox.

So, if you replace this code:

if (arrChecks[i].value == "on") 
{
    arrChecks[i].checked = 1;
} else {
    arrChecks[i].checked = 0;
}

With this:

arrChecks[i].checked = !arrChecks[i].checked;

It should work. You should use true and false instead of 0 and 1 for this.

Upvotes: 20

meouw
meouw

Reputation: 42140

To toggle a checkbox or you can use

element.checked = !element.checked;

so you could use

if (attribute == elementName)
{
    arrChecks[i].checked = !arrChecks[i].checked;
} else {
    arrChecks[i].checked = false;
}

Upvotes: 5

Spikolynn
Spikolynn

Reputation: 4173

Also make sure you test it both in firefox and IE. There are some nasty bugs with JS manipulated checkboxes.

Upvotes: 0

steve_c
steve_c

Reputation: 6255

You should be evaluating against the checked property of the checkbox element. 

for (i=0; i<arrChecks.length; i++)
{
    var attribute = arrChecks[i].getAttribute("xid")
    if (attribute == elementName)
    {
        // if the current state is checked, unchecked and vice-versa
        if (arrChecks[i].checked)
        {
            arrChecks[i].checked = false;
        } else {
            arrChecks[i].checked = true;
        }

    } else {
        arrChecks[i].checked = false;
    }
}

Upvotes: 27

ForYourOwnGood
ForYourOwnGood

Reputation: 40392

I am not sure what the problem is, but I am pretty sure this will fix it.

for (i=0; i<arrChecks.length; i++)
    {
        var attribute = arrChecks[i].getAttribute("xid")
        if (attribute == elementName)
        {
            if (arrChecks[i].checked == 0)  
            {
                arrChecks[i].checked = 1;
            } else {
                arrChecks[i].checked = 0;
            }

        } else {
            arrChecks[i].checked = 0;
        }
    }

Upvotes: 0

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