Oracle Apex - Dynamically Color Text field

It is often useful to highlight certain fields when certain (usually incorrect) values are entered as a form of on the fly validation. 

Suppose you had a fairly large form with many fields many of which only accept numbers. It would be much more user friendly if you could alert end-users to incorrect values as they enter it, rather than let them submit and have a big list of invalid entries to sift through.

1) Put the following code in page header.

<script language="JavaScript" type="text/javascript">

function setCol(pThis)

{

var vv = $v(pThis);

var cls = '#'+pThis;

if(isNaN(vv))

{

$(cls).css("background-color","red");

}

else

{

$(cls).css("background-color","white");

}

}

</script>

2) Create Dynamic Action with following configuration:

1. Type Advanced (for pre-4.2)
2. Event: change
3. Selection Type: item
4. Item(s): P1_ENAME, P1_MOB (comma seperate the list of items)
5. True Action: 
1. Action: Execute Javascript Code
2. Code: setCol(this.triggeringElement.id);
6. Affected Items:
1. Pick the items in #4 above.

What this does is basically highlight textfield when non-numeric characters are entered (isNAN). 

Here is how it should look like if implemented properly. You can take this and do more fancy stuff like validating against regex. 

http://apex.oracle.com/pls/apex/f?p=21796:1