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Disable button by clearing checkbox

tsubasa
P: 64
I have a form where a user can select items via a check box. Once an item is checked it will enable a button to appear so that the user can add the items to a shopping cart. I have the first part of the JavaScript working which allows the button to appear if the checkbox is true.

The problem that I am having is when I decide to deselect the last remaining box. It does not disable the add button. The first part works, the second part does nothing. Also, there are no JavaScript errors.

-Tsu

Expand|Select|Wrap|Line Numbers
  1.  
  2. function boxChecked(field)
  3. {
  4.   var 1 = 0;
  5.   if(field[i].checked = true)
  6.   {
  7.    var x=document.getElementById("mybutton")
  8.    x.disable=false;
  9.   }
  10.   else
  11.   if(field[i].checked = false)
  12.   {
  13.   var x=document.getElementById("mybutton")
  14.   x.disable=true;
  15.  
  16.  
Jul 12 '12 #1
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4 Replies


Dormilich
Expert Mod 5K+
P: 8,639
thatís because = is the assignment operator.

tip: reverse variable and value.
Expand|Select|Wrap|Line Numbers
  1. if (box.checked = false) // no error
  2.  
  3. if (false = box.checked) // error: cannot assign to a constant
Jul 12 '12 #2

tsubasa
P: 64
Hello Dormilich,

Although this does not produce an error, it does not work. The same remains even with your recommendation. The first part works, but the 2nd part does nothing. Thanks for replying anyhow.

-Tsu
Jul 13 '12 #3

Dormilich
Expert Mod 5K+
P: 8,639
er, my code was not meant as a working demonstration. it is an example to demonstrate the problem.

you are just mistaking the assignment operator for the comparison operator. the given code shows a possibility to write code in a way that you can’t mistake one for the other.
Jul 13 '12 #4

tsubasa
P: 64
Understood,

Thanks!
Jul 13 '12 #5

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