Problem with ordering headings in a sorted list

Question

I am building a web application in which I build a sorted list out of an object like this:
{head: {subhead: [list_items], subhead: [list_items]}, head: {subhead: [list_items]}} .
My problem is that I have to ensure the headings and subheading always follow in a certain order. This is complicated by the fact that headings and subheadings that may be added later on also need to follow this order. So the only way I could think to inform the parser of the order would be to give it some data like this:
{heads: [head1, head2, head3], subheads: {head1: [subhead1_1, subhead1_2], head2: [subhead2_1, subhead2_2, subhead2_3]}} ,
but that strikes me as overly verbose and repeating data that would be in the original data structure.

Answer 1

You might as well use an array (or your own structure) for this since you want it to be ordered. Your own structure might look like:

function Head(name) {
  this.name = name;
  this.arr = [];
}

So instead of the structure:

var thing = {
  food: {fruit: [apples, oranges], vegetables: [carrots, peas]},
  animals: {domestic: [cat, dog], wild: [lion, bear]}
}

You might do:

var thing = [new Head('food'), new Head('animals')]

Then:

thing[0].arr.push('apples'); 
thing[0].arr.push('oranges');

etc.

Of course you don't have to make a class, since you can actually attach properties to arrays in javascript. But making the datastructure would be a bit more of a pain.