Javascript regular expression: remove first and last slash

return theString.replace(/^\/|\/$/g, '');

"Replace all (/.../g) leading slash (^\/) or (|) trailing slash (\/$) with an empty string."

There's no real reason to use a regex here, string functions will work fine:

var string = "/banking/bonifici/italia/";
if (string.charAt(0) == "/") string = string.substr(1);
if (string.charAt(string.length - 1) == "/") string = string.substr(0, string.length - 1);
// string => "banking/bonifici/italia"

See this in action on jsFiddle.

References:

• String.substr
• String.charAt

In case if using RegExp is not an option, or you have to handle corner cases while working with URLs (such as double/triple slashes or empty lines without complex replacements), or utilizing additional processing, here's a less obvious, but more functional-style solution:

const urls = [
  '//some/link///to/the/resource/',
  '/root',
  '/something/else',
];

const trimmedUrls = urls.map(url => url.split('/').filter(x => x).join('/'));

console.log(trimmedUrls);

In this snippet filter() function can implement more complex logic than just filtering empty strings (which is default behavior).

Word of warning - this is not as fast as other snippets here.

Just in case that someone needs a premature optimization here...

http://jsperf.com/remove-leading-and-trailing-slashes/5

var path = '///foo/is/not/equal/to/bar///'
var count = path.length - 1
var index = 0

while (path.charCodeAt(index) === 47 && ++index);
while (path.charCodeAt(count) === 47 && --count);

path = path.slice(index, count + 1)