extjson converter in js for mongo shell

extjson.js

function convertExtJson(o){
	// if it's an array, loop over each item
	if(o.constructor == Array){
    out = []
    for(var i=0; i<o.length;i++){
      out.push(convertExtJson(o[i]))
    }
    return out
  }else if(o.constructor == Object){
    // if it's an object, replace each key one by one
    numKeys = Object.keys(o).length
    if(numKeys == 1){
      if("$date" in o){
        return ISODate(convertExtJson(o["$date"]))
      }else if("$numberLong" in o){
        return NumberLong(o["$numberLong"])
      }else if("$code" in o){
        // TODO
      }else if("$numberInt" in o){
        return NumberInt(o["$numberInt"])
      }else if("$undefined" in o){
        return undefined
      }else if("$maxKey" in o){
        return MaxKey()
      }else if("$minKey" in o){
        return MinKey()
      }
    }
    for(var k in o){
        if (!o.hasOwnProperty(k)) {
          continue
        }
        o[k] = convertExtJson(o[k])
    }
    return o
  }else{
    return o
  }
}