freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/explore-differences-between-the-var-and-let-keywords.md

id, title, challengeType, forumTopicId, dashedName

id	title	challengeType	forumTopicId	dashedName
587d7b87367417b2b2512b3f	Explore Differences Between the var and let Keywords	1	301202	explore-differences-between-the-var-and-let-keywords

--description--

One of the biggest problems with declaring variables with the var keyword is that you can easily overwrite variable declarations:

var camper = "James";
var camper = "David";
console.log(camper);

In the code above, the camper variable is originally declared as James, and is then overridden to be David. The console then displays the string David.

In a small application, you might not run into this type of problem. But as your codebase becomes larger, you might accidentally overwrite a variable that you did not intend to. Because this behavior does not throw an error, searching for and fixing bugs becomes more difficult.

A keyword called let was introduced in ES6, a major update to JavaScript, to solve this potential issue with the var keyword. You'll learn about other ES6 features in later challenges.

If you replace var with let in the code above, it results in an error:

let camper = "James";
let camper = "David";

The error can be seen in your browser console.

So unlike var, when you use let, a variable with the same name can only be declared once.

--instructions--

Update the code so it only uses the let keyword.

--hints--

var should not exist in the code.

(getUserInput) => assert(!getUserInput('index').match(/var/g));

catName should be the string Oliver.

assert(catName === 'Oliver');

catSound should be the string Meow!

assert(catSound === 'Meow!');

--seed--

--seed-contents--

var catName = "Oliver";
var catSound = "Meow!";

--solutions--

let catName = "Oliver";
let catSound = "Meow!";