[Javascript] Calculating large number of different values

[Triche Osborne]

Fred Newtz wrote:
> 
> I started trying to name my textboxes but I keep feeling that I need to make
> my looping structure before I make the names for the text boxes.  What
> should come first?  The field names/ids or the looping structure?  What is a
> good way to plan for the names use and how you are looping through them?
> 

Interesting question. It's one of those things that is easier to do than 
to explain because it's not a process I go through explicitly and there 
isn't just one way to do it.
	For me, the naming comes first. I generally consider 3 things: input 
data, output requirements and language resources and constraints.

Input Data:
(1) Attendance broken down by day of week per meal per age group
(2) Food group (servings per child) broken down by meal per age group

Output Requirements:
XHTML:
(1) Attendance => same as input
(2) Food Group => input * Attendance

Display Heirarchy:
------------------
Age Group => Meal => Food Group

PHP: ?

Language Resources and Constraints:
XHTML
-----
Resource: NAME attribute
Constraint: If using NAME['arrayIndex'] format, must be accessed 
through  	DOM with getElementById or getElementsByTagName; that 
is, no 			direct access through form array.
Resource: ID attribute
Constraint: Cannot use array format. Invisible to PHP.
Resource: CLASS attribute
Constraint: Cannot use array format. Invisible to PHP.

JavaScript
----------
Resource: instance property
Constraint: Arrays pass by reference. Invisible to PHP.

If PHP has to process edited textbox input in some way, I'm limited to 
using the NAME attribute for any data that must be processed by both 
languages, and I may need to use a single form so that the submit button 
processes everything. If not, then I'm free to use other attributes and 
break up the output into a form per age group. Since I don't know 
whether PHP has to get this information or not, I'm going to stick with 
one form and the NAME attribute.

The first thing I'd try to do is to get a good match between my array 
names and textboxes, while at the same time trying to simplify the 
arrays as much as possible. The arrays can be looked at in different ways:

PlanPart[day][meal][agegroup]
PlanPart[day][agegroup][meal]

In some cases, one may be more helpful than the other. In this case, for 
instance, you're using the first way, but your output hierarchy matches 
the second. I'd try to make them match.
	Suppose the first entry in your PlanPart array looked something like 
this: PlanPart["Monday"]['age0'] = [30, 30, 30, 30, 20, 15]
	That means that the first input box in the attendance column of your 
form could be named "age00". Since the array name and the day of the 
week are external to the form, this name gives you simple access to the 
secondary and tertiary levels of the PlanPart array.
	
In the same way, modifying the food group arrays can do the same thing. 
Let's say the milk array looks something like this . . .

var milk = new Array([3, 2, 2, 1, 1], [2, 2, 2, 1, 1],  [2, 2, 2, 1, 1])

. . . where the primary level represents the age groups and the 
secondary level the meal. You could then name your first row, first 
column input box "milk00" (or "milk[0][0]").

	In the places where the meal consists of more than one food group, I 
think I'd eliminate all but the primary attendance box. After all, if 
the child is present for the meal, he is present for all of the food 
groups. This eliminates complications with naming the other boxes.
	At this point, you can modify the original function to deal with the 
new levels OR (and I just thought of this as I was thinking on this), 
you could rewrite it to grab all of the INPUT tags, then flip through 
the inputs one by one, filling them out as you go. If you choose the 
latter, you might want to rearrange the column order to make it easy to 
"save" the attendance figure where it need to apply to multiple food 
groups within a single meal.

Triche