Alert when checkbox is ticked by user

Question

I have a checkbox in a website that is not controlled by me.But it can be modified by javascript,html,jquery..etc(they have provided web applet for doing so)

Threre is a checkbox which can be identified with an ID 'Zcb_1'. All i wasnt if the user checks the checkbox only then an alert should come. W hen the user navigates to the page. the checkbox might be ticked or unticked, but i dont care then.

I need this alert only when the state of the checkbox changes from unticked to ticked. I am not much into jquery and ajax, so if this can be done done simply( imean just using javascript)it would be great.

EDIT: How can the same be impletmentd if I have a dropdown(Select) with values 'Y' , 'N'and blank and then alert should come when the 'Y' is selected by user.(Alert when the value is changed from blank or 'N' to 'Y'

Answer 1

As you say you can use jQuery (I also suppose what you ask is technically feasible ), this would be the code:

$(function(){
   $("#your_checkbox_id").change(function(){
       if($(this).is(":checked")){
          alert("Checkbox checked!!");
       }
   });
});

Cheers

Answer 2

Just do:

document.getElementById("IDHERE").onchange = function() {
    if (!this.checked)
        alert("Unchecked");
}

Answer 3

Maybe this is what you want:

if (document.getElementById('CheckBox1').checked){
   alert("Checkbox ticked");
}
else{
    alert("Checkbox not ticked");
}

Answer 4

您可以使用标准的javascript onclick方法，然后检查以查看this.checked，然后调用程序。

Answer 5

Using javascript:-

<script type="text/javascript">  
//This is done to make the following JavaScript code compatible to XHTML. <![CDATA[ 
function verifybox() 
{ 
if (document.myform.checkbox1.checked) 
{ 
alert('This box is checked.'); 
} 
else 
{ 
alert('This box is not checked.'); 
} 
} 
//]]>  
</script>  
<form name="myform" action="#">  
<input type="checkbox" name="checkbox1" />Check here  
<p>  
<input type="button" value="Verify Box" name="Mybutton"  
onclick="verifybox()" /></p>  
</form>