Need simple answer for my Javascript, please?

In my CF application, I need to add a javascript for text fields validation.
I already have the script, the bad news is there has been another javascript for that same text fields where its
functionality is for number calculation. This existing script uses OnKeyUp for those text fields where I'm supposed to also use OnKeyUp for validation check

I'm no javascript expert and have tried to put 2 OnKeyUp within the same text fields and my attempt causes the validation script not functioning.
How can I use my validation script for the same text field where calculation script has used OnKeyUp event handler? Please help!

Here is what I can't figure out:

//My script to prevent user from entering special characters when submitting data

<script language="JavaScript">

var mikExp = /[$\\@\\\#%\^\&\*\(\)\[\]\+\_\{\}\`\~\=\|-]/;
function checkeachfield(val) {
var strPass = val.value;
var strLength = strPass.length;
var lchar = val.value.charAt((strLength) - 1);
if(lchar.search(mikExp) != -1) {
var tst = val.value.substring(0, (strLength) - 1);
val.value = tst;
}
}
//
</script>

// Below is part of the existing script for number calculation. I'm not suppose to modify this script:
<script language="JavaScript">

function calctotal() {
document.cost.f2.value = document.cost.f1.value * 0.25;
document.cost.f5.value = document.cost.f4.value * 0.25;
document.cost.al2.value = document.cost.al1.value * 0.25;
document.cost.al5.value = document.cost.al4.value * 0.25;
document.cost.nf2.value = document.cost.nf1.value * 0.25;
document.cost.nf5.value = document.cost.nf4.value * 0.25;
document.cost.nal2.value = document.cost.nal1.value * 0.25;
document.cost.nal5.value = document.cost.nal4.value * 0.25;

var f1 = parseFloat(document.cost.f1.value);
var f2 = parseFloat(document.cost.f2.value);
var f4 = parseFloat(document.cost.f4.value);
var f5 = parseFloat(document.cost.f5.value);
var f8 = parseFloat(document.cost.f8.value);
var al1 = parseFloat(document.cost.al1.value);
...............etc
</script>

<!--- I don't know how to call these 2 functions from these text fields --->

<input name="f1" type="text" onKeyUp="calctotal();" value="0"
onKeyUp="javascript:checkeachfield(xyz.f1);"> ???

<input name="f2" type="text" onKeyUp="calctotal();" value="0"
onKeyUp="javascript:checkeachfield(xyz.f2);"> ???

<input name="f3" type="text" onKeyUp="calctotal();" value="0"
onKeyUp="javascript:checkeachfield(xyz.f3);"> ???

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More text fields need to be check for special chars