如果使用变量时IF不起作用

Question

The second if does not work, and the third one does not work if I put a variable instead of "2" I was trying to put if (cont==len) but does not work. Which is the problem?

function alert(Vform){
var i=0;
var cont=0;
var len=Vform.length;
for (i=0;i<=len;i++){
    if (Vform.elements[i].checked!=true){
    cont=cont+1
    }
}
if (cont!=2){
    window.alert("Please select date and time");
}

}

Answer 1

Try to do these changes:

function alert(Vform)
{
var cont=0;
var len=Vform.length;
for (var i=0;i<=len;i++)
{
    if (Vform.elements[i].checked!=true)
    {
        cont++;
    }
}
if (cont != 2)
{
    alert("Please select date and time");
}
}

Answer 2

Your for loop should be like this.

for (i=0;i<len;i++){
   //code
}

It should check i<len and not i<=len because array element start with zero based index