javascript - Regex, replace all words starting with @

Question

I have this regular expression that puts all the words that starts with @ into span tags. I've accomplished what is needed but i'm not sure that i completely understand what i did here.

content.replace(/(@S+)/gi,"<span>$1</span>")

1. The () means to match a whole word, right?
2. The @ means start with @.
3. The S means "followed by anything until a whitespaces" .

But how come that if don't add the + sign after the S , it matches only the first letter?

Any input would be appreciated .

Answer 1

S is any non-whitespace character and a+ means one or more of a. So

@S -> An @ followed by one non-whitespace character.

@S+ -> An @ followed by one or more non-whitespace characters