create deep values in an object with a string

gistfile1.txt

var assert = require('assert')

var set = function(obj, key, val) {

  var split = key.split('.'),
    prop = obj,
    prevIndex;

  //single length key needs no depth traversal

  if(split.length == 1) {

    prop[key] = val;
    return obj;
  }

  split.forEach(function(part, index) {

    var partWithoutIndex,
      partAryIndex,
      i = 0,
      hasIndex = typeof prevIndex === 'number';

    if(part.match(/\[.{1,}]/) instanceof Array ) {

      partAryIndex = parseInt(part.match(/\[(.{1,})]/)[1], 10);
      partWithoutIndex = part.replace(/\[.{1,}]/, '');

      //console.log('partAryIndex:', partAryIndex);
      //console.log('partWithoutIndex:', partWithoutIndex);

      if(typeof prop[partWithoutIndex] === 'undefined') {

        prop[partWithoutIndex] = [];
      }

      if(index === split.length - 1) {

        prop[partWithoutIndex][partAryIndex] = val;
      }else {

        prop = prop[partWithoutIndex];
      }

    }else {

      if(index === split.length - 1) {

        if(hasIndex) {
          prop[prevIndex] = {};
          prop[prevIndex][part] = val;
        }else {
          prop[part] = val;
        }
      } else {

        if(hasIndex) {

          prop[prevIndex] = {};

          if(typeof prop[prevIndex][part] === 'undefined') {

            prop[prevIndex][part] = {};
          }

          prop = prop[prevIndex][part];
        }else {

          if(typeof prop[part] === 'undefined') {

            prop[part] = {};
          }

          prop = prop[part];
        }

      }
    }

    prevIndex = partAryIndex;
  })

  return obj;
};

var res = set({}, 'thing.foo.bar.plop.glop', 'baz');

assert.equal(res.thing.foo.bar.plop.glop, 'baz');

var res = set({}, 'justin[1].foo', 'meow');

assert.equal(res.justin[1].foo, 'meow');

var res = set({}, 'justin[12].foo.gloob', 'meow');

assert.equal(res.justin[12].foo.gloob, 'meow');

var res = set({}, 'justin[12].foo.gloob[3]', 'rarara');

assert.equal(res.justin[12].foo.gloob[3], 'rarara');

var res = set({}, 'justin[12].foo.gloob[3].za', 'rarara');

assert.equal(res.justin[12].foo.gloob[3].za, 'rarara');

var res = set({}, 'justin[12].foo.gloob[3][4][2].za', 'rarara');

assert.equal(res.justin[12].foo.gloob[3].za, 'rarara');