freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/es6/declare-a-read-only-variable-with-the-const-keyword/index.md

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title: Declare a Read-Only Variable with the const Keyword
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# Declare a Read-Only Variable with the const Keyword

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## Problem Explanation

Change all the variables to `let` or `const` and rename `sentence`.


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## Hints

### Hint 1

*   Replace `var` for string with read-only `const`.

### Hint 1

*   Replace `var` in `for` loop to `let`.

### Hint 1

*   Common convention is to name `const` variables with ALL CAPS.



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## Solutions

<details><summary>Solution 1 (Click to Show/Hide)</summary>

```javascript
function printManyTimes(str) {
  "use strict";
  const SENTENCE = str + " is cool!";
  for (let i = 0; i < str.length; i += 2) {
    console.log(SENTENCE);
  }
}
printManyTimes("freeCodeCamp");
```

#### Code Explanation

By using `const` on `sentence` we can make it read-only and by using `let` on `i` inside the for loop we can avoid using `var` all together. For added code clarity we can also change `sentence` to `SENTENCE` to show that it is a constant.

#### Relevant Links

*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/const' target='_blank' rel='nofollow'>const</a>
*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let' target='_blank' rel='nofollow'>let</a>

</details>