Adding numbers from a text object value?

[hd65]

I have several text boxs that display a number (subtotal)and I need to add all the (subtotals) and display that number in another textbox. Is this close??
form.text1box.value = form.text2box.value + form.text3box.value....I know it's not right I get NaN error.

 

[rbobbitt]

here's a function to do what you want:

function calculate(form)
{
[tab]var i;
[tab]var res=0;

[tab]// Loop through everything in the form
[tab]for (i=0;i<form.length;++i) {
[tab][tab]// only look at text elements and ignore total field
[tab][tab]if (form.elements.type==&quot;text&quot; && form.elements.name!=&quot;total&quot {
[tab][tab][tab]// skip entries that are empty or don't contain a number
[tab][tab][tab]if (!isNaN(form.elements.value) && form.elements.value != &quot;&quot {
[tab][tab][tab][tab]res+=eval(form.elements.value);
[tab][tab][tab]}
[tab][tab]}
[tab]}
[tab]return(res);
}

Here's some sample HTML to use it:

<form>
enter a number: <input type=&quot;text&quot; onChange=&quot;this.form.total.value=calculate(this.form);&quot;>
enter a number: <input type=&quot;text&quot; onChange=&quot;this.form.total.value=calculate(this.form);&quot;>
enter a number: <input type=&quot;text&quot; onChange=&quot;this.form.total.value=calculate(this.form);&quot;>
total: <input type=&quot;text&quot; name=&quot;total&quot;><input type=&quot;button&quot; value=&quot;Calculate!&quot; onClick=&quot;calculate(this.form);&quot;>
</form>

Instead of having the script just skip entries that are blank or don't contain a number, you'll want to require (within the constraints of javascript) the user, to fill in an acceptable value. Also, you can implement the calculation method in a number of ways. You could remove all the onChange events and just have them click a button. Or add onFocus, onBlur events etc. Make sure that your total field name matches the condition above in the calculate function.

I haven't tested this in Netscape browsers. It's been awhile since I've written anything in javascript and for some reason, the type property of form.elements seems suspect.

Hope this helped!