Replace backlash with 2 backslashes in JavaScript [duplicate]

I want to display strings exactly as they are, without special characters (i.e. d, n, s) being recognized.

For example, say I have this string with a newline character:

let someString = 'hellonthere';

I need to escape the newline character, so I need to replace the backslash with 2 backslashes to get hello\nthere.

Solution Attempt 1:

let replacedString = someString.replace(/\/g, "\\"), 

but replacedString still recognizes the newline character:

hello
there

when what I want to see for replacedString is hello\nthere.

Solution Attempt 2:

let rawString = String.raw`hellonworld`.replace(/\/g,"\\");

This works well, because rawString is hello\nworld. However, the template literal part should be a variable (someString) and when I include someString like so:

let rawString = String.raw`${someString}`.replace(/\/g,"\\");

I get this for rawString:

hello
there

How do I simply replace a backslash with 2 backslashes? I’ve already scoured several posts on Stack Overflow and can’t seem to find a solution to this problem.

Thanks in advance!