Javascript recursive object is defined test

Question

I wrote the method below, and was wondering whether a better way exists/best practice tips

_objectIsDefined = function (obj, path) {
 if (typeof path !== 'undefined') {
 // if we have been given a specific object path then recursively search it
 var pathSplit = path.split("."),
 scope = undefined;
 scope = obj;
 for (i = 0; i < pathSplit.length; i++) {
 if (typeof scope[pathSplit[i]] === 'undefined') {
 return false;
 } else if (i == pathSplit.length - 1 && typeof scope[pathSplit[i]] !== 'undefined') {
 return true;
 }
 scope = obj[pathSplit[i]];
 }
 return false;
 } else if (typeof obj !== 'undefined') {
 // if we've just been given an object and no path then return whether
 // its defined or not...
 return true;
 } else {
 return false;
 }
}
 // Usage
var isDefined = _objectIsDefined(myObject);
var isDefinedDeep = _objectIsDefined(myObject, "somenested.child.property.name");

Answer 1

First of all, what you are doing is not recursive (self-calling). It's iterative (looping).

And here's a shorter version of it:

_objectIsDefined = function (obj, path) {
 if (!obj) return false; // no object, return false
 if (obj && !path) return true; // has object, no path, return true
 // I suggest var per variable for clarity
 var props = path.split(".");
 var currentObject = obj;
 for (var i = 0; i < props.length; ++i) {
 //store the next property, evaluate and break out if it's undefined
 currentObject = currentObject[props[i]];
 if (!currentObject) return false;
 }
 // If the loop did not break until the last path, then the path exists
 return true;
}

• Phil: My mistake - thanks for the correction on semantics. :) Enjoying the optimization you have performed, works great.