Cartesian product of objects in javascript

Question

I need to generate a complete set of variants based on a list of N attributes, while keeping the attribute name intact.

Answer 1

Once you get rid of the ' 'i' is a global var issue', you can get to the result with this code for instance :

var input = [
    { 'colour' : ['red', 'green'] },
    { 'material' : ['cotton', 'wool', 'silk'] },
    { 'shape' : ['round', 'square', 'rectangle'] }
];

function cartesianProduct(input, current) {
   if (!input || !input.length) { return []; }

   var head = input[0];
   var tail = input.slice(1);
   var output = [];

    for (var key in head) {
      for (var i = 0; i < head[key].length; i++) {
            var newCurrent = copy(current);         
            newCurrent[key] = head[key][i];
            if (tail.length) {
                 var productOfTail = 
                         cartesianProduct(tail, newCurrent);
                 output = output.concat(productOfTail);
            } else output.push(newCurrent);
       }
     }    
    return output;
}

function copy(obj) {
  var res = {};
  for (var p in obj) res[p] = obj[p];
  return res;
}


console.log(cartesianProduct(input));