Home » HTML » HTML_QuickForm_SelectFilter » Bug #4566

[2005-06-10 14:41 UTC] studio at peptolab dot com

Description:
------------
The filter function will slow down, naturally, when the select
element contains many hundreds or even thousands of elements.
This delay can force, for example, 5 long-ish delays for a 5
letter filter word, as the filter is applied for each
keystroke.

It would be great to add a default behaviour to allow a small
timer (300 - 400milliseconds) to delay the filter to allow
enough time to capture many user keystrokes before it is fully
applied.

Reproduce code:
---------------
I have modified the javascript code below (a hack to get it to work) that demonstrates the desired behaviour:-

...existing code...

<script type="text/javascript">
//<![CDATA[
// begin javascript for filtered select
var values = new Array();
var QF_SelectFilterObj, QF_SelectFilterValue, QF_SelectFilterTimeout, QF_SelectFilterMustStart;
var QF_SelectFilterCnt = 0;

function QF_SelectFilterTimeOut(str, list, muststart) {
QF_SelectFilterCnt++;
QF_SelectFilterObj = list;
QF_SelectFilterValue = str;
QF_SelectFilterMustStart = muststart;
QF_SelectFilterTimeout = setTimeout("QF_SelectFilter(QF_SelectFilterValue, QF_SelectFilterObj, QF_SelectFilterMustStart)",350);
}

function QF_SelectFilter(str, list, muststart) {
QF_SelectFilterCnt--;
if (QF_SelectFilterCnt) { return false; }
str = QF_SelectFilterValue.value;
if (!values[list.name]) {
// first use of this list, we store initial elements

...continue...

The 'QF_SelectFilterCnt' allows for all keystrokes to set and clear timeouts before proceeding to apply the filter. I think there's certainly a more graceful way to handle the timeout syntax, but you get the idea!

Expected result:
----------------
The above code snippet will implement a Javascript timer to
allow extra keystrokes before the buffer is applied.

It would be also in keeping with the flexibility of the class
to allow a 'setDelay' method to the Quickform object to tweak
the delay as required.