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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");
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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;
}
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  • \$\begingroup\$ My mistake - thanks for the correction on semantics. :) Enjoying the optimization you have performed, works great. \$\endgroup\$ – Phil Oct 14 '13 at 16:10

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