Object has-property-deep check in JavaScript

Question

Let's say we have this JavaScript object:

var object = {
   innerObject:{
       deepObject:{
           value:'Here am I'
       }
   }
};

How can we check if value property exists?

I can see only two ways:

First one:

if(object && object.innerObject && object.innerObject.deepObject && object.innerObject.deepObject.value) {
    console.log('We found it!');
}

Second one:

if(object.hasOwnProperty('innerObject') && object.innerObject.hasOwnProperty('deepObject') && object.innerObject.deepObject.hasOwnProperty('value')) {
    console.log('We found it too!');
}

But is there a way to do a deep check? Let's say, something like:

object['innerObject.deepObject.value']

or

object.hasOwnProperty('innerObject.deepObject.value')

Answer 1

There isn't a built-in way for this kind of check, but you can implement it easily. Create a function, pass a string representing the property path, split the path by ., and iterate over this path:

Object.prototype.hasOwnNestedProperty = function(propertyPath) {
  if (!propertyPath)
    return false;

  var properties = propertyPath.split('.');
  var obj = this;

  for (var i = 0; i < properties.length; i++) {
    var prop = properties[i];

    if (!obj || !obj.hasOwnProperty(prop)) {
      return false;
    } else {
      obj = obj[prop];
    }
  }

  return true;
};

// Usage:
var obj = {
  innerObject: {
    deepObject: {
      value: 'Here am I'
    }
  }
}

console.log(obj.hasOwnNestedProperty('innerObject.deepObject.value'));