Javascript checkboxes

I want to know the number of checboxes checked in javascript. If only one checkbox is checked then it should show an alert message, otherwise it should do the processing. I tried if(names[i].checked>2) but it is not 开发者_如何学运维working.. Please help.

function insert_slide(ed, height, width)

{ var img=new Array();

var names=document.getElementsByName('image_id');


for(i=0;i<names.length;i++)
{
if(names[i].checked)
{
    img[i] = "<IMG SRC='" + names[i].value + "'";






    if(height != '') {
        img[i] += " height='" + height + "'";
    }
    if(width != '') {
        img[i] += " width='" + width + "'"; 
    }
    img[i] += " style='margin: 5px;' >";

    editor.nicCommand("insertHTML", img[i]);
}}
    hide_lightwindow();
}

---

A solution could be the following:

function check(form) {
var sum = 0;
max = form.box.length;
  for(i=0; i<max; i++) {
    if(form.box[i].checked) {
      sum+=1;
    }
  }
  if (sum==1) {alert("one is checked")}
  else {alert("more than one are checked") }
}

Get the lenght of all chechboxes in a form. Then check with a for loop, if there are checked chechboxes, for each one it finds adds 1 in the variable sum

Demo: http://jsbin.com/ezafal/2

---

If names contains the checkboxes, this could be a counter:

var countChecked = 0;
for (var i=0;i<names.length;i++){
  countChecked += /checkbox/i.test(names[i].type) && names[i].checked ? 1 : 0;
}
if (countChecked === 1) {
 // alert something
} else {
 // proces
}

---

So easy with JQuery. You should check into it as your primary JS framework:

if($('input[type=checkbox]:checked').length == 1)
{
    alert('Only one checked');
}
else
{
    // Do code
}