fn.js

var objectify = function () {
        var glob = typeof arguments[0] == 'object' ? arguments[0] : window;
        var a, b, i, l, n,v, ext = arguments;
        for (a in ext) {
            i = ext[a];
            l = null, n = null;
            if (typeof i == 'string') {
                if (i.match('.')) {
                    l = i.split('.');
                    for (b in l) {
						v = null;
                    	v = l[b].split('=');
                    	if(v.length>1){
                    		l[b] = v[0];
                    	}
                        if (n && l[b] in n) {
                            n = n[l[b]];
                            continue;
                        } else if (b == 0 && l[b] in glob) {
                            n = glob[l[b]];
                            continue;
                        }
                        if(v[1]){
                        	n[l[b]] = v[1];
                        	continue;
                        }
                        n = (n ? n[l[b]] = {} : glob[l[b]] = {});                        
                    }
                }
            }
        }
        return glob;
    };

implementation.js

var OBJ = {};

objectify(  OBJ, 
            'pension.plan.year1.total.payout=100000', 
            'insurance.private.house', 
            'bank.accounts.transactions.march.length=34', 
            'pension.payout.now=10'
         );

ResultingObject.json

{
  "pension": {
    "plan": {
      "year1": {
        "total": {
          "payout": "100000"
        }
      }
    },
    "payout": {
      "now": "10"
    }
  },
  "insurance": {
    "private": {
      "house": {}
    }
  },
  "bank": {
    "accounts": {
      "transactions": {
        "march": {
          "length": "34"
        }
      }
    }
  }
}