--- id: 5d79253a98bd9fdf7ce68d0a title: Part 137 challengeType: 0 isHidden: true --- ## Description
We've used recursion in `range`, but recursion can have performance issues in JavaScript. If performance is an issue, you should try to use a higher order function like `reduce`, and if you can't do that, you'll probably have to use a for/while loop. While we don't expect the user to enter particularly large numbers so that performance is an issue, we're going to refactor `range` as an exercise. Replace the body of `range` with `start`.
## Instructions
## Tests
```yml tests: - text: See description above for instructions. testString: assert(/constrange=\(start,end\)=>start(;|const)/.test(code.replace(/\s/g, ""))); ```
## Challenge Seed
```html ```
### Before Test
```html Spreadsheet
```
### After Test
```html ```
## Solution
```html ```