Using a string to call an object

Question

I am trying to create a program that defines the variable finalResult based on variable input. The input variable should call on an object inside of object A:

var input = "";
var A = {
   AA: {
      result: 0
   },
   AB: {
      result: 1
   }
}
var finalResult = A.input.result;

So if input = "AA", then the final result should be 0, but if input = "AB", then the final result should be 1.

You should read about [Javascript property accessors](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors). Use bracket notation: in your case, `var finalResult = A[input].result` — Ian, Oct 03 '19 at 03:15

score 0 · Accepted Answer · answered Oct 03 '19 at 03:17

You can do A[input].result, which assumes the value of input is present as a property in A. If the property isn’t present you’ll get an error trying to access result on undefined. You can guard against this by OR’ing it with an empty object:

(A[input] || {}).result // undefined if A[input] isn’t present

Using a string to call an object

1 Answers1