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Calculating adding numbers in text fields using javascript

Posted on 2009-04-10
8
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Last Modified: 2012-05-06
I have a form with textfields that each gets populated with a number if/when a person makes a selection from various list menus.  I would like to create a grand total field that calculates the textfields.  Right now, textfields are originally defaulted to 0.00

What I want to accomplish:
1. Total field will add/calculate total selected textfields
2. Total field is originally defaulted to 0.00
3. Total field automatically updates after a textfield has a value selected/entered

Below is code I am trying to work with but encountering issues with.
<script type="text/javascript">
function func1()
{
document.form.answerfield1 = eval(document.form.textfield1 + document.form.textfield2 + document.form.textfield3)
}
</script>
<p>
  <input type="text" name="textField1">
  <input type="text" name="textField2">
  <input type="text" name="textField3" onChange="JavaScript:func1();">
</p>
<p>Total 
  <input type="text" name="answerfield1">
</p>

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Comment
Question by:arendt73
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8 Comments
 
LVL 41

Expert Comment

by:HonorGod
ID: 24116582
Something like this perhaps?
<html>
<body>
 
<form name='myform' action=''>
  1: <input type="text" id="textField1"><br>
  2: <input type="text" id="textField2"><br>
  3: <input type="text" id="textField3" onChange="func1()"><br>
Total 
  <input type="text" id="answerField1">
</form>
 
 
<script type="text/javascript">
function field( id ) {
  var ele = document.getElementById( id )
  if ( !ele ) {
    alert( 'Element not found. id="' + id + '"' )
  }
  return ele
}
function result( val ) {
  alert( 'result() "' + val + '"' )
  return ( val == '' ) ? 0.0 : parseFloat( val )
}
function func1() {
  var val1 = result( field( 'textField1' ).value )
  var val2 = result( field( 'textField2' ).value )
  var val3 = result( field( 'textField3' ).value )
  field( 'answerField1' ).value = val1 + val2 + val3
}
</script>
 
</body>
</html>

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Author Comment

by:arendt73
ID: 24116716
Very close.  I do not need need the prompts after the values are totaled at the end.  I would like the total box to update automatically after an amount is entered.  Also, there is a chance that a textfield my not contain a value (defaulted to 0.00).    
0
 
LVL 41

Expert Comment

by:HonorGod
ID: 24116761
Understood.  The "alert()" was just added to help me understand what was happening.  How about:
<html>
<body>
 
<form name='myform' action=''>
  1: <input type="text" id="textField1"><br>
  2: <input type="text" id="textField2"><br>
  3: <input type="text" id="textField3" onChange="func1()"><br>
Total 
  <input type="text" id="answerField1">
</form>
 
 
<script type="text/javascript">
function field( id ) {
  var ele = document.getElementById( id )
  if ( !ele ) {
    alert( 'Element not found. id="' + id + '"' )
  }
  return ele
}
function result( val ) {
  return ( val == '' ) ? 0.0 : parseFloat( val )
}
function func1() {
  var val1 = result( field( 'textField1' ).value )
  var val2 = result( field( 'textField2' ).value )
  var val3 = result( field( 'textField3' ).value )
  field( 'answerField1' ).value = val1 + val2 + val3
}
</script>
 
</body>
</html>

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LVL 41

Expert Comment

by:HonorGod
ID: 24116789
Note though, that the answer will only be updated when the textField3 input field is modified.  If you want changes to any of them to be reflected, you could use something like:
<html>
<body>
 
<form name='myform' action=''>
  1: <input type="text" id="textField1" onChange="func1()"><br>
  2: <input type="text" id="textField2" onChange="func1()"><br>
  3: <input type="text" id="textField3" onChange="func1()"><br>
Total 
  <input type="text" id="answerField1">
</form>
 
 
<script type="text/javascript">
function field( id ) {
  var ele = document.getElementById( id )
  if ( !ele ) {
    alert( 'Element not found. id="' + id + '"' )
  }
  return ele
}
function result( val ) {
  return ( val == '' ) ? 0.0 : parseFloat( val )
}
function func1() {
  var val1 = result( field( 'textField1' ).value )
  var val2 = result( field( 'textField2' ).value )
  var val3 = result( field( 'textField3' ).value )
  field( 'answerField1' ).value = val1 + val2 + val3
}
</script>

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Author Comment

by:arendt73
ID: 24117186
Is there a way to make the total field (answerField) total with cents (.00)?  Right now, after the textfields have data, the final total adds/calculates without cents.  
0
 
LVL 41

Expert Comment

by:HonorGod
ID: 24117388
Certainly, the following indicates that the value should include 2 (and only 2) places after the decimal place.
field( 'answerField1' ).value = ( val1 + val2 + val3 ).toFixed( 2 )

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LVL 41

Accepted Solution

by:
HonorGod earned 500 total points
ID: 24118371
Anything else?
0
 
LVL 41

Expert Comment

by:HonorGod
ID: 24118697
Thank you for the grade & points.

Good luck & have a Happy Easter
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