---
title: Spinal Tap Case
---
# Spinal Tap Case
---
## Problem Explanation
Convert the given string to a lowercase sentence with words joined by dashes.
#### Relevant Links
* String global object
* JS Regex Resources
* JS String Prototype Replace
* JS String Prototype ToLowerCase
---
## Hints
### Hint 1
Create a regular expression for all white spaces and underscores.
### Hint 2
You will also have to make everything lowercase.
### Hint 3
The tricky part is getting the regular expression part to work, once you do that then just turn the uppercase to lowercase and replace spaces with underscores using `replace()`.
---
## Solutions
Solution 1 (Click to Show/Hide)
```javascript
function spinalCase(str) {
// Create a variable for the white space and underscores.
var regex = /\s+|_+/g;
// Replace low-upper case to low-space-uppercase
str = str.replace(/([a-z])([A-Z])/g, "$1 $2");
// Replace space and underscore with -
return str.replace(regex, "-").toLowerCase();
}
// test here
spinalCase("This Is Spinal Tap");
```
#### Code Explanation
* **regex** contains the regular expression `/\s+|_+/g`, which will select all white spaces and underscores.
* The first `replace()` puts a space before any encountered uppercase characters in the string **str** so that the spaces can be replaced by dashes later on.
* While returning the string, another `replace()` replaces spaces and underscores with dashes using **regex**.
Solution 2 (Click to Show/Hide)
```javascript
function spinalCase(str) {
// Replace low-upper case to low-space-uppercase
str = str.replace(/([a-z])([A-Z])/g, "$1 $2");
// Split on whitespace and underscores and join with dash
return str
.toLowerCase()
.split(/(?:_| )+/)
.join("-");
}
// test here
spinalCase("This Is Spinal Tap");
```
#### Code Explanation
* Similar to the first solution, the first `replace()` puts a space before any encountered uppercase characters in the string **str** so that the spaces can be replaced by dashes later on.
* Instead of using `replace()` here to replace whitespace and underscores with dashes, the string is `split()` on the regular expression `/(?:_| )+/` and `join()`-ed on `-`.
#### Relevant Links
* JS String Prototype Split
* JS Array Prototype Join
Solution 3 (Click to Show/Hide)
```javascript
function spinalCase(str) {
// "It's such a fine line between stupid, and clever."
// --David St. Hubbins
return str
.split(/\s|_|(?=[A-Z])/)
.join("-")
.toLowerCase();
}
```
#### Code Explanation
* Split the string at one of the following conditions (_converted to an array_)
* a whitespace character [`\s`] is encountered
* underscore character [`_`] is encountered
* or is followed by an uppercase letter [`(?=[A-Z])`]
* Join the array using a hyphen (`-`)
* Lowercase the whole resulting string
#### Relevant Links
* String#split
* RegExp
* Arrray#join
* String#toLowerCase