Question

suppose I have a object:

obj:{
   child:{
      x:12,
      y:50
   },
   key1:"value1",
   key2:"value2"
}

if I want to traverse the object,like:

for (var i in obj) {

}

How can I judge whether the object have child object,so I could traverse it.I know I could use hasOwnProperty method, but in this situation, I have no idea about what the child object name is .

Answer 1

You can use this to check if a property contains an Object:

for (var i in obj) {
    if(obj.hasOwnProperty(i) && obj[i] instanceof Object) {
        // obj[i] is a child object
    }
}

A note of precaution: remember that Functions and Arrays are both Objects in Javascript. You can test individually for those using instanceof Function and instance of Array.