---
id: 56533eb9ac21ba0edf2244c9
title: Accessing Object Properties with Variables
challengeType: 1
guideUrl: 'https://www.freecodecamp.org/guide/certificates/accessing-objects-properties-with-variables'
---
## Description
Another use of bracket notation on objects is to access a property which is stored as the value of a variable. This can be very useful for iterating through an object's properties or when accessing a lookup table.
Here is an example of using a variable to access a property:
var dogs = {
Fido: "Mutt",
Hunter: "Doberman",
Snoopie: "Beagle"
};
var myDog = "Hunter";
var myBreed = dogs[myDog];
console.log(myBreed); // "Doberman"
Another way you can use this concept is when the property's name is collected dynamically during the program execution, as follows:
var someObj = {
propName: "John"
};
function propPrefix(str) {
var s = "prop";
return s + str;
}
var someProp = propPrefix("Name"); // someProp now holds the value 'propName'
console.log(someObj[someProp]); // "John"
Note that we do not use quotes around the variable name when using it to access the property because we are using the value of the variable, not the name.
## Instructions
Use the playerNumber variable to look up player 16 in testObj using bracket notation. Then assign that name to the player variable.
## Tests
```yml
tests:
- text: playerNumber should be a number
testString: 'assert(typeof playerNumber === "number", "playerNumber should be a number");'
- text: The variable player should be a string
testString: 'assert(typeof player === "string", "The variable player should be a string");'
- text: The value of player should be "Montana"
testString: 'assert(player === "Montana", "The value of player should be "Montana"");'
- text: You should use bracket notation to access testObj
testString: 'assert(/testObj\s*?\[.*?\]/.test(code),"You should use bracket notation to access testObj");'
- text: You should not assign the value Montana to the variable player directly.
testString: 'assert(!code.match(/player\s*=\s*"|\"\s*Montana\s*"|\"\s*;/gi),"You should not assign the value Montana to the variable player directly.");'
- text: You should be using the variable playerNumber in your bracket notation
testString: 'assert(/testObj\s*?\[\s*playerNumber\s*\]/.test(code),"You should be using the variable playerNumber in your bracket notation");'
```
## Challenge Seed
```js
// Setup
var testObj = {
12: "Namath",
16: "Montana",
19: "Unitas"
};
// Only change code below this line;
var playerNumber; // Change this Line
var player = testObj; // Change this Line
```
### After Test
```js
console.info('after the test');
```
## Solution
```js
var testObj = {
12: "Namath",
16: "Montana",
19: "Unitas"
};
var playerNumber = 16;
var player = testObj[playerNumber];
```