CODEWITHSUNDEEP
javascriptcalculator
CarlRyds
CarlRyds

Reputation: 217

How would I take what's in the Exc. VAT box and add 20% and put the resulting amount in the Inc. VAT box?

I have three boxs, two of them imput boxs and one is a selector, here's a picture...

enter image description here

For arguments sake lets say we select 20%

How would i take what's in the Exc. VAT box and add 20% and put the resulting amount in the Inc. VAT box live, so if you change whats in Exc. VAT then Inc. VAT recalculates.

Example: Exc Rate Inc. 2.00 + 20% = 2.40

It would be nice if it could go the other way aswell, so you put an amount in Inc. VAT and it divides it by 1.20 (20%) into Exc. VAT

Upvotes: 0

Views: 743

Answers (2)

Rango
Rango

Reputation: 3907

<form name="calculator">
    <input name="exc_vat" type="text" onkeyup="calc_inc()" />
    <select name="vat" onchange="calc_two()">
        <option value="1.2">20%</option>
        <option value="1.05">5%</option>
        <option value="1">0%</option>
    </select>
    <input name="inc_vat" type="text" onkeyup="calc_exc()" />
</form>

<script type="text/javascript">
function calc_inc(){
    var frm = document.forms.calculator;
    frm.inc_vat.value = (frm.vat.value * frm.exc_vat.value).toFixed(2);
}
function calc_exc(){
    var frm = document.forms.calculator;
    frm.exc_vat.value = (frm.inc_vat.value / frm.vat.value).toFixed(2);
}
function calc_two(){
    var frm = document.forms.calculator;
    if (frm.exc_vat.value != '') calc_inc(); else if (frm.inc_vat.value != '') calc_exc();
}
</script>

Upvotes: 1

Eric
Eric

Reputation: 97575

var exc = document.getElementById(...)
var inc = document.getElementById(...)

inc.onKeyup = function() {
     exc.value = inc.value / 1.2;
}
exc.onKeyup = function() {
     inc.value = exc.value * 1.2;
}

Depending on how you want this to behave, you might want onInput or onChanged instead.

Upvotes: 0

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