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autochecking checkbox based on form field being filled in

Posted on 2004-10-20
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Last Modified: 2010-08-05
hi all,
I have a page that contains a quantity field as well as an 'add' checkbox field that users use to add the item to their shopping cart. I want to get rid of this checkbox requirement by having it autocheck when a value is entered in to the quantity field. What would be the correct syntax to do this?

Here's a code snippet that's currently on the page:

<input type="text" name="Qty" size="4" maxlength="4" value="">
 
<input type="checkbox" name="AddBook" value="#ISBN#"> I need this form element to both autocheck when a form quantity field is entered in. I also need this checkbox to be hidden as well.

Thanks!
0
Comment
Question by:bluskyGuy
  • 4
  • 4
  • 2
  • +2
12 Comments
 
LVL 15

Expert Comment

by:justinbillig
ID: 12362920
<input type="text" name="Qty" size="4" maxlength="4" value="" onchange="if(this.value != ''){ formname.AddBook.checked=true;}else{formname.AddBook.checked=false;}">
0
 
LVL 15

Expert Comment

by:justinbillig
ID: 12362929
<div style="visibility: hidden"><input type="text" name="Qty" size="4" maxlength="4" value=""></div>
0
 
LVL 8

Accepted Solution

by:
RozanaZ earned 2000 total points
ID: 12362985
Checkboxes are visible:

<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
<script>
      function test(obj, checkId)
      {
            if (obj.value != "")
            {
                  document.getElementById(checkId).checked = true;
            }
            else
            {
                  document.getElementById(checkId).checked = false;
            }
      }      
</script>
</HEAD>
<BODY>
<form>
      <input type="checkbox" name="AddBook" id="book1" value="#ISBN#">
      <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book1')">
      <br>
      <input type="checkbox" name="AddBook" id="book2" value="#ISBN#" > 
      <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book2')">
      <br>
      <input type="checkbox" name="AddBook" id="book3" value="#ISBN#" > 
      <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book3')">
</form>
</BODY>
</HTML>

-------------------

Checkboxes invisible:


<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
<script>
      function test(obj, checkId)
      {
            if (obj.value != "")
            {
                  document.getElementById(checkId).checked = true;
            }
            else
            {
                  document.getElementById(checkId).checked = false;
            }
      }      
</script>
</HEAD>
<BODY>
<form>
      <input type="checkbox" name="AddBook" id="book1" value="#ISBN#" style="display:none">
      <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book1')">
      <br>
      <input type="checkbox" name="AddBook" id="book2" value="#ISBN#" style="display:none">
      <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book2')">
      <br>
      <input type="checkbox" name="AddBook" id="book3" value="#ISBN#" style="display:none">
      <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book3')">
</form>
</BODY>
</HTML>
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LVL 36

Expert Comment

by:Zyloch
ID: 12363018
Hi bluskyGuy,

Something like this?

I guess you would call this on onchange inside the textbox, like this: checkTxtField(this);

function checkTxtField(obj) {
   for (var i=0;i<obj.form.elements.length;i++) {
      if (obj.form.elements[i]==obj) {
         if (obj.value!="") {
            obj.form.elements[i+1].checked=true;
            obj.form.elements[i+1].style.visibility='hidden';
         } else {
            obj.form.elements[i+1].checked=false;
            obj.form.elements[i+1].style.visibility='visible';
         }
         break;
      }
   }
}

Regards,
Zyloch
0
 
LVL 32

Expert Comment

by:ldbkutty
ID: 12363073
without a trim you will get checked even if you enter a white space in the textbox. you will need both onkeyup as well as onchange event (to make sure the checkbox is checked even if copy, paste the values in the textbox).

<html>
<head>
<script language="JavaScript" type="text/javascript">
<!--
function makeChecked() {
 var theForm = document.myform;
 if(trim(theForm.Qty.value) != "")
   theForm.AddBook.checked = true;
 else
   theForm.AddBook.checked = false;
}
function trim(str) {
  return str.replace(/^\s*|\s*$/g,"");
}
//-->
</script>
</head>
<body>
<form name="myform" method="post" action="" >
Quantity: <input type="text" name="Qty" size="4" maxlength="4" value="" onkeyup="makeChecked()" onchange="makeChecked()"/> <br>
Add: <input type="checkbox" name="AddBook" value="#ISBN#"/>
</form>
</body>
</html>
0
 
LVL 8

Expert Comment

by:RozanaZ
ID: 12363173
yes, I agree with ldbkutty
trim should be used

<HTML>
<HEAD>
<TITLE></TITLE>
<script>
     function test(obj, checkId)
     {
          if (obj.value.trim != "")
          {
               document.getElementById(checkId).checked = true;
          }
          else
          {
               document.getElementById(checkId).checked = false;
          }
     }    
</script>
</HEAD>
<BODY>
<form>
     <input type="checkbox" name="AddBook" id="book1" value="#ISBN#" style="display:none">
     <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book1')">
     <br>
     <input type="checkbox" name="AddBook" id="book2" value="#ISBN#" style="display:none">
     <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book2')">
     <br>
     <input type="checkbox" name="AddBook" id="book3" value="#ISBN#" style="display:none">
     <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book3')">
</form>
</BODY>
</HTML>
0
 
LVL 8

Expert Comment

by:RozanaZ
ID: 12363181
bluskyGuy ,
Do you want a number validation for quantity field?
0
 

Author Comment

by:bluskyGuy
ID: 12363223
Thanks all for the recommendations. I'm giving them a shot now.
If you could give me a number validation for the quantity field that would be great!
Thanks again!
0
 
LVL 8

Expert Comment

by:RozanaZ
ID: 12363385
<HTML>
<HEAD>
<TITLE></TITLE>
<script>
     function test(obj, checkId)
     {            
              if (isNaN((obj.value)))
              {
                  alert("Numbers only");
                  obj.focus();
                  return;
              }
              if (obj.value != "")
          {
            
               document.getElementById(checkId).checked = true;
          }
          else
          {
               document.getElementById(checkId).checked = false;
          }
     }  
</script>
</HEAD>
<BODY>
<form>
     <input type="checkbox" name="AddBook" id="book1" value="#ISBN#" style="display:none">
     <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book1')">
     <br>
     <input type="checkbox" name="AddBook" id="book2" value="#ISBN#" style="display:none">
     <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book2')">
     <br>
     <input type="checkbox" name="AddBook" id="book3" value="#ISBN#" style="display:none">
     <input type="text" name="Qty" size="4" maxlength="4" value="" onChange="test(this, 'book3')">
</form>
</BODY>
</HTML>
0
 

Author Comment

by:bluskyGuy
ID: 12363556
For some reason the checkboxes aren't autochecking themselves.
I'm using this for the qty field syntax:
 <input type="text" name="Qty" size="4" maxlength="4" value="" onchange="if(this.value != ''){ formname.AddBook.checked=true;}else{formname.AddBook.checked=false;}">

Any suggestions?
0
 

Author Comment

by:bluskyGuy
ID: 12363656
the autocheckbox is now working! The issue that I notice is that the user has to click out of the qty field box in order for the checkbox to be checked...do you know how to make it so that as soon as a number is entered in the checkbox is checked?
0
 

Author Comment

by:bluskyGuy
ID: 12363701
Nevermind, i solved the problem!
Thanks everyone for the help!
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