Someone explain me this regex, please

JavaScript
1 
let hello = "   Hello, World!  ";
let wsRegex = /^\s+|\s+$/g; // Change this line
let result = hello.replace(wsRegex,""); // Change this line
console.log(result);

This gives the expected result, but don’t know how.
here is the link to the problem
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/regular-expressions/remove-whitespace-from-start-and-end

2

^ matches the start of the string
\s+ matches one or more spaces
So ^\s+ matches one or more spaces at the beginning of the string.

Then $ matches the end of the string
So \s+$ matches one or more spaces at the end.

| means to match either ^\s+ or \s+$. Then the regex matches spaces either at the start or the end.

3

Lets break it down:
Here is what you have:

let hello = " Hello, World! ";

When you look at the content of the variable closely, you can see that there are some extra spaces. Right?

Yes!

So the purpose of the exercise is to remove the spaces in the beginning and the end.

Do you agree?

Yes

So, how do we do that without Regex?

Use trim method. (Not recommended for this exercise)

And, how do we do that with Regex?

That’s the question we’ll answer.

Earlier on during your lessons you got to see how to use them at different levels. Now, you need to combine both the removal of white spaces in front and the removal of white spaces at the end.

let wsRegex = / ^\s+ | \s+$ /g; // Change this line

The wsRegex should take care of it.
You still remember that the Regex happens within these / /

Now, lets remove the white spaces at the back:

/^\s+ / will change " Hello, World! " to "Hello, World! "

Good but not enough.

What else?

The spaces left in the front.

\s+$ will change "Hello, World! " to "Hello, World!"

Great.

And the g in front of regex makes the search global for all occurrences.

But Regex doesn’t remove those white spaces. Regex select the elements needed and the element we needed to select were the white spaces.

Where are the elements selected?

They are in the wsRegex variable

What do we do with the selected element?

We need to replace them with empty space in the hello string

let result = hello.replace(wsRegex,""); // Change this line

The console gives you the desired result:

console.log(result);