Javascript method to check if a chained object is defined.

is_defined.js

/**
 * Take string input in varName and determine whether it is defined object in Javascript
 * ...like isDefined('foo.bar.baz');
 * Better than doing if(foo && foo.bar && foo.bar.baz){} 
 * @param {String} varName
 * @return {boolean}
 * @author Bilal Soylu
 */
function isDefined(varName) {
  var retStatus = false;
  if (typeof varName == "string") {
    try {
      var arrCheck = varName.split(".");
      var strCheckName = "";
      for (var i=0; i < arrCheck.length; i++){
        strCheckName = strCheckName + arrCheck[i];
        //check wether this exist
        if (typeof eval(strCheckName) == "undefined") {
          //stop processing
          retStatus = false;
          break;     
        } else {
          //continue checking next node
          retStatus = true;
          strCheckName = strCheckName + ".";
        }
      }
    } catch (e) {
      //any error means this var is not defined
      retStatus = false;
    }
  } else {   
    throw "the varName input must be a string like myVar.someNode.anotherNode[]";
  }
  return retStatus;
}