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75 lines
1.8 KiB
Markdown
75 lines
1.8 KiB
Markdown
---
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id: 587d7b87367417b2b2512b3f
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title: Explore Differences Between the var and let Keywords
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challengeType: 1
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forumTopicId: 301202
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dashedName: explore-differences-between-the-var-and-let-keywords
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---
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# --description--
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One of the biggest problems with declaring variables with the `var` keyword is that you can easily overwrite variable declarations:
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```js
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var camper = "James";
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var camper = "David";
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console.log(camper);
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```
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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`.
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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.
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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.
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If you replace `var` with `let` in the code above, it results in an error:
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```js
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let camper = "James";
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let camper = "David";
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```
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The error can be seen in your browser console.
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So unlike `var`, when you use `let`, a variable with the same name can only be declared once.
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# --instructions--
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Update the code so it only uses the `let` keyword.
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# --hints--
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`var` should not exist in the code.
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```js
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assert.notMatch(code, /var/g);
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```
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`catName` should be the string `Oliver`.
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```js
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assert.equal(catName, 'Oliver');
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```
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`catSound` should be the string `Meow!`
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```js
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assert.equal(catSound, 'Meow!');
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```
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# --seed--
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## --seed-contents--
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```js
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var catName = "Oliver";
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var catSound = "Meow!";
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```
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# --solutions--
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```js
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let catName = "Oliver";
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let catSound = "Meow!";
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```
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