nested string parser

parser.js

var string = 'name:stock, vars:colors:red, vars:colors:blue,vars:sizes:44, really:nasty:nested';

function parse(array) {
  return array
    .map(function(item) {
      var parts = item.split(':');

      return {
        key: parts.shift(),
        value: parts.join(':')
      };
    })
    .reduce(function(prev, curr) {
      var pair = prev.find(function(item) {
        return item.key === curr.key;
      });

      if (!pair) {
        pair = {
          key: curr.key,
          value: [curr.value]
        };
        prev.push(pair);
      } else {
        if (!~pair.value.indexOf(curr.value)) {
          pair.value.push(curr.value);
        }
      }

      return prev;
    }, [])
    .reduce(function(prev, curr) {
      if (Array.isArray(curr.value) && curr.value.join('').contains(':')) {
        curr.value = parse(curr.value);
      }
      if (!prev[curr.key]) {
        prev[curr.key] = curr.value;
      }

      return prev;
    }, {});
}

var obj = parse(string.split(', '));

// { name: ['stock'], vars: { colors: ['red', 'blue'], sizes: ['44'] }, really: { nasty: ['nested'] } };
console.log(obj);