---
id: 587d7dad367417b2b2512b76
title: Make Code More Reusable with the this Keyword
challengeType: 1
---
## Description
The last challenge introduced a method to the duck object. It used duck.name dot notation to access the value for the name property within the return statement:
sayName: function() {return "The name of this duck is " + duck.name + ".";}
While this is a valid way to access the object's property, there is a pitfall here. If the variable name changes, any code referencing the original name would need to be updated as well. In a short object definition, it isn't a problem, but if an object has many references to its properties there is a greater chance for error.
A way to avoid these issues is with the this keyword:
let duck = {
name: "Aflac",
numLegs: 2,
sayName: function() {return "The name of this duck is " + this.name + ".";}
};
this is a deep topic, and the above example is only one way to use it. In the current context, this refers to the object that the method is associated with: duck.
If the object's name is changed to mallard, it is not necessary to find all the references to duck in the code. It makes the code reusable and easier to read.
## Instructions
Modify the dog.sayLegs method to remove any references to dog. Use the duck example for guidance.
## Tests
```yml
- text: dog.sayLegs() should return the given string.
testString: 'assert(dog.sayLegs() === "This dog has 4 legs.", "dog.sayLegs() should return the given string.");'
- text: Your code should use the this keyword to access the numLegs property of dog.
testString: 'assert(code.match(/this\.numLegs/g), "Your code should use the this keyword to access the numLegs property of dog.");'
```
## Challenge Seed
```js
let dog = {
name: "Spot",
numLegs: 4,
sayLegs: function() {return "This dog has " + dog.numLegs + " legs.";}
};
dog.sayLegs();
```
## Solution
```js
let dog = {
name: "Spot",
numLegs: 4,
sayLegs () {
return 'This dog has ' + this.numLegs + ' legs.';
}
};
dog.sayLegs();
```