[Javascript] Monitor an offsetHeight value

[Guillaume]

Paul,

Thank you for taking some time to post this useful reply...
This surely has helped a lot...

Regards,

Guillaume
> At 1/15/2007 06:52 AM, Guillaume wrote:
>> Here's my function below re-aranged according to your replies...
>> I still don't understand why, when checkOptSli() is called, I always 
>> get the else statement... Not being able
>> to compare an initial value to a listened one...
>
> ...
>
>> function checkOptSli() { // This is fired when a user clicks a link
>>
>>  var sto2 = 0;
>
> Why are you setting this variable?  You don't use it for anything and 
> because it's local it can't be used anywhere else in your script.
>
>
>> sto2ID = setTimeout("checkOptJ();", 2000);
>
> This sets sto2ID equal to the setTimeout() id, but it is a pointless 
> assignment statement because sto2ID is never used again inside this 
> function and being local it cannot be used anywhere else (although you 
> attempt to do so).
>
> Your script suggests that you believe setTimeout("checkOptJ();", 
> 2000); will return the result of function checkOptJ(), however 
> according to the manual setTimeout() returns "the ID of the timeout, 
> which can be used with window.clearTimeout."
> http://developer.mozilla.org/en/docs/DOM:window.setTimeout
>
>
>> }
>>
>> function checkOptJ() {
>>
>>    var optsh0 = checkOptK;
>
> This statement sets optsh0 equal to the TEXT of function checkOptK().  
> Probably what you want is:
>
>         var optsh0 = checkOptK();
>
> to get the RETURN VALUE from function checkOptK().  See:
> http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Guide:Defining_Functions 
>
>
>
>>    optsh3 = optsh0;// Initial value (offsetHeight) of element
>
> No, this sets optsh3 equal to the TEXT of function checkOptK().  
> Display its value with alert() to see what I mean.
>
>
>>    var optsh1 = 0;
>
> This is a pointless assignment statement since you do not use optsh1 
> again within this function and, being local, it cannot be used 
> anywhere else.
>
>
>>    var optsh1ID = setTimeout("checkOptL();", 2000);
>
> Again this sets optsh1ID equal to the ID of this setTimeout() call, a 
> value that is really only useful to clearTimeout().
>
>
>>    optsh4 = optsh1ID;// Value to be listened to and compared to the 
>> previous one above
>
> What's your purpose in passing the setTimeout() ID from one variable 
> to another?
>
>
>>          if ( optsh4 > optsh3 ) {
>
> This compares the id of the previous setTimeout() call to the text of 
> function checkOptK(), a nonsense comparison.
>
> You need to rewrite your code to return the changing heights of your 
> elements.
>
>
>
>>              alert( "things have moved" );
>>            }
>>          else {
>>          alert( "quiet" );
>>            }
>> }
>>
>>
>>
>>   function checkOptK(){ // Fired on the onload so we have a value as 
>> starting point
>>
>>      var opts1 = document.getElementById("options");
>>
>>      moveBy1 = opts1.offsetHeight;
>>
>>      posTn3 = 0 - moveBy1;
>>      parseInt( posTn3 );
>
> parseInt() is a function that returns a value.  It does not affect the 
> value passed to it.  You probably mean:
>
>         posTn3 = parseInt( posTn3 );
>
> http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Guide:Predefined_Functions:parseInt_and_parseFloat_Functions 
>
>
>
>
>>      return posTn3;
>>
>>      }
>>
>>  function checkOptL(){ // Looped inside a setTimeout to see if this 
>> value is changing...                        // And compare it inside 
>> the checkOptJ()function to the checkOptK()resulting value
>>
>>      var opts2 = document.getElementById("options");
>>
>>      moveBy2 = opts2.offsetHeight;
>>
>>      posTn4 = 0 - moveBy2;
>>
>>      parseInt( posTn4 );
>>
>>      return posTn4;
>>
>>      }
>
> checkOptK() and checkOptL() performs identical functions -- you can 
> make them a single function called from two different places in your 
> code.
>
>
> Guillaume, I strongly suggest that you read the JavaScript and DOM 
> documentation, and also that you use alert() to display values of your 
> variables as you go along to help you debug your code.  It seems clear 
> from your code that you need to strengthen your understanding of basic 
> JavaScript syntax.
>
> Core JavaScript 1.5 Guide
> http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Guide
>
> Gecko DOM Reference
> http://developer.mozilla.org/en/docs/Gecko_DOM_Reference
>
>
> Regards,
> Paul
> __________________________
>
> Juniper Webcraft Ltd.
> http://juniperwebcraft.com
>
> _______________________________________________
> Javascript mailing list
> Javascript at LaTech.edu
> https://lists.LaTech.edu/mailman/listinfo/javascript
>