Backslashes - Regular Expression - Javascript

Question

I wanted to build a JS function concatting a list of arguments to a valid path (since I could not be sure whether a part of the path is given with or without slashes)

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Answer 1

You should use a regular expression literal (/.../) instead of a string literal ('...' or "...") in the call to replace. Strings have their own interpretation of backslashes that kicks in before the regular expression constructor gets a crack at it, so you need an extra level of quoting.

Match one backslash, regular expression literal: /\\/

Match one backslash, regular expression in a string: '\\\\'

But in a regex literal, you also have to put backslashes in front of the forward slashes, since forward slashes are the delimiter for the whole thing:

path += arguments[i].replace(/(\\|\/)$|^(\\|\/)/, "") + "/";

Or, if you're married to the use of strings for some reason, this should also work:

path += arguments[i].replace("(\\\\|/)$|^(\\\\|/)", "") + "/";

As a side note, when your alternatives are single characters, (x|y) is overkillish; you can just use character classes: [xy]. In which case you get this:

path += arguments[i].replace(/[\\\/]$|^[\\\/]/, "") + "/";

path += arguments[i].replace("[\\\\/]$|^[\\\\/]", "") + "/";