JavaScript replace() method dollar signs

Question

I have a string like aman/gupta and I want to replace it to aman$$gupta and for that I am using JavaScript replace method as follows:

let a = "aman/gupta"
a = a.replace("/", "$")
console.log(a) // 'aman$gupta'

a = "aman/gupta"
a = a.replace("/", "$$")
console.log(a) // 'aman$gupta'

a = "aman/gupta"
a = a.replace("/", "$$$")
console.log(a) // 'aman$$gupta'

Why are the 1st and 2nd case identical and I get the expected result when I use $$$ instead of $$?

Answer 1

It’s because $$ inserts a literal "$".

So, you need to use:

a = "aman/gupta";
a = a.replace("/", "$$$$"); // "aman$$gupta"

---

See the following special patterns:

Pattern	Inserts
$$	Inserts a "$".
$&	Inserts the matched substring.
$`	Inserts the portion of the string that precedes the matched substring.
$'	Inserts the portion of the string that follows the matched substring.
$n	Where n is a non-negative integer less than 100, inserts the _n_th parenthesized submatch string, provided the first argument was a RegExp object.
$<Name>	Where Name is a capturing group name. If the group is not in the match, or not in the regular expression, or if a string was passed as the first argument to replace instead of a regular expression, this resolves to a literal (e.g., "$<Name>").

Answer 2

Also you can use split and join for better performance and $ isn't special for those functions.

var a = "aman/gupta"
a = a.split('/').join('$$')
alert(a); // "aman$$gupta"