Find all combinations of options in a loop

Question

I\'m looking for the best way to loop through a bunch of options to make sure that I hit all available options.

I\'ve created a feature that allows a client to build

Answer 1

You want the Cartesian Product of all your arrays.

I have a page discussing this, including implementations in JavaScript, on my site:
http://phrogz.net/lazy-cartesian-product

For example, to iterate through them all quickly in "forward" order, you can use:

hats   = ['fez','fedora']
shirts = ['t-shirt','long']
pants  = ['shorts','jeans']
shoes  = ['sneaker','loafer']

lazyProduct( [hats,shirts,pants,shoes], function(hat,shirt,pant,shoe){
  // Your function is yielded unique combinations of values from the arrays
  console.log(hat,shirt,pant,shoe);
});

function lazyProduct(sets,f,context){
  if (!context) context=this;
  var p=[],max=sets.length-1,lens=[];
  for (var i=sets.length;i--;) lens[i]=sets[i].length;
  function dive(d){
    var a=sets[d], len=lens[d];
    if (d==max) for (var i=0;i

The output:

fez t-shirt shorts sneaker
fez t-shirt shorts loafer
fez t-shirt jeans sneaker
fez t-shirt jeans loafer
fez long shorts sneaker
fez long shorts loafer
fez long jeans sneaker
fez long jeans loafer
fedora t-shirt shorts sneaker
fedora t-shirt shorts loafer
fedora t-shirt jeans sneaker
fedora t-shirt jeans loafer
fedora long shorts sneaker
fedora long shorts loafer
fedora long jeans sneaker
fedora long jeans loafer
fez t-shirt shorts sneaker
fez t-shirt shorts loafer

This is identical to the results of:

hats.forEach(function(hat){
  shirts.forEach(function(shirt){
    pants.forEach(function(pant){
      shoes.forEach(function(shoe){
        console.log(hat,shirt,pant,shoe);
      });
    });
  });
});

or (for older browsers):

for (var h=0;h

…but it supports an arbitrary number of arrays defined at runtime. (And if you're using the first "lazy" implementation from my site, you can pick out items at random, iterate in reverse, or easily stop iteration at any point.)