So i've read a handful of SO posts and some blogs, but still can't figure out why my code isn't working.

My code:

function myFunct(d) {
    if (typeof d.parent.name == "undefined") {
        console.log("undefined") ;} else { console.log("defined") ;}
    }

d is an object that looks something like:

Object { 
children: Object, 
count: 676
}

I've tried using (!d.parent.name), hasOwnProperty, ===, and as above using typeof. Any suggestions?

The error I recieve is TypeError: d.parent.name is undefined

UPDATE:

Ok thanks everyone for the input, and my apologies if the question was confusing. I was actually looking for d.parent.parent but tried to simplify the question by using d.parent. I think the problem is that d.parent is not defined so it doesn't even get to d.parent.parent. Sorry for not being more specific!

So i've read a handful of SO posts and some blogs, but still can't figure out why my code isn't working.

My code:

function myFunct(d) {
    if (typeof d.parent.name == "undefined") {
        console.log("undefined") ;} else { console.log("defined") ;}
    }

d is an object that looks something like:

Object { 
children: Object, 
count: 676
}

I've tried using (!d.parent.name), hasOwnProperty, ===, and as above using typeof. Any suggestions?

The error I recieve is TypeError: d.parent.name is undefined

UPDATE:

Ok thanks everyone for the input, and my apologies if the question was confusing. I was actually looking for d.parent.parent but tried to simplify the question by using d.parent. I think the problem is that d.parent is not defined so it doesn't even get to d.parent.parent. Sorry for not being more specific!

• javascript
• function
• if-statement
• undefined

• @ForceMagic I receive the same error. – As3adTintin Commented Apr 11, 2016 at 21:15
• 1 typeof Object === 'undefined' is a valid way to use typeof – NickSlash Commented Apr 11, 2016 at 21:17
• @NickSlash sry, my bad :) – ForceMagic Commented Apr 11, 2016 at 21:18
• @NickSlash Thanks, unfortunately I still get the same TypeError – As3adTintin Commented Apr 11, 2016 at 21:18
• can you give this a try? if (d.parent && typeof d.parent.name === 'undefined') – NickSlash Commented Apr 11, 2016 at 21:20

4 Answers 4

If you want an undefined-safe check all the way down your object tree, you can use:

if( typeof( ((d || {}).parent || {}).name ) === 'undefined') {

}

If you have the luxury of having Lodash at your disposal:

var d = { 
     parent: {
          name: "Joe"
     }
};

if ( typeof (_.get(d, "parent.name")) === 'undefined' ) {

}

Try to check all children with logical OR

if (typeof d == "undefined" ||
    typeof d.parent == "undefined" ||
    typeof d.parent.name == "undefined") {
// ...
}

if(typeof x === 'undefined')

Use this, it checks for type as well as value, thats what you need.

I believe the error is the property identifier parent. Are you sure your object has the property? The identifier d may be invalid because parent doesn't exists.