Javascript using variable as key to get nested object value

Question

Assume I have the following object:

var jsonObj = {  
  "response":{  
    "result":{  
      "status":{
        "name": "Eric"
      }
    }
  }
}

And now i'd like to dynamically access a nested property:

jsonKey = "response.result.status.name";
console.log("the status is: " + jsonObj.jsonKey);  //I cannot call jsonObj.jsonKey here

Is there any way to achieve this?

@btzr Even if this is my jsonValue? `response.result.status.name` — tiger_groove, Mar 20 '18 at 02:15
Possible duplicate of [Dynamically access object property using variable](https://stackoverflow.com/questions/4244896/dynamically-access-object-property-using-variable) — btzr, Mar 20 '18 at 02:16
then yes, see this answer for more info: https://stackoverflow.com/a/4244912/6836839 — btzr, Mar 20 '18 at 02:21
if `status.name == "theKey"` then this are the same: `obj.theKey == obj[status.name] == obj["theKey"]` ^^ — btzr, Mar 20 '18 at 02:25
mozilla docs: [Property Accessors](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_Accessors) — btzr, Mar 20 '18 at 02:29
@btzr I added my jsonObj above, you mentioned if `status.name` is a string or not. What if it isn't a string? — tiger_groove, Mar 20 '18 at 03:36
you are trying to access to an object property by the name, right? — btzr, Mar 20 '18 at 03:44
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/167130/discussion-between-btzr-and-kkmoslehpour). — btzr, Mar 20 '18 at 03:46

connexo · Accepted Answer · 2018-03-20T14:42:03.963

You cannot access a deeply nested property as simple as you expect. Instead you need to use the obj[propertyNameAsString] syntax to dive deeper into the response one by one.

This would be one way of getting there:

let response = {
  "response": {
    "method": "GetStatus",
    "module": "Module",
    "data": null,
    "result": {
      "status": {
        "name": "Eric"
      },
      "id": 1
    },
    "result_code": {
      "error_code": 0
    }
  }
}

let keyString = "response.result.status.name"
let keyArray = keyString.split('.'); // [ "response", "result", "status", "name" ]
var result = response;

for (key of keyArray) {
  result = result[key]
}

console.log(result)

Please be aware that this is not failsafe against cases where one of those strings in keyArray does not exist as a property on the preceding object.

this breaks in some cases (like objects being null). the question posted by @btzr constains an answer with a safer implementation: https://stackoverflow.com/a/45322101/347508 — kritzikratzi, Mar 20 '18 at 13:06

Javascript using variable as key to get nested object value

1 Answers1