This function encodes special characters. In addition, it encodes the following characters: , / ? : @ & = + $ # .

This definition is vague as to what special characters are. It sounds like a comparison between encodeURI and encodeURIComponent. Both will correctly escape as %5C, so you don't have to worry about backslashes.

encodeURI will leave the listed characters as it is assumed that the entire URI is being encoded:

encodeURI('http://example.com/foo bar/baz.html');

//produces http://example.com/foo%20bar/baz.html

encodeURIComponent will escape everything as it is assumed that the string is to be used as part of a query-string:

'http://example.com?foo=' + encodeURIComponent('http://example.com/fizz/buzz.html');

//produces http://example.com?foo=http%3A%2F%2Fexample.com%2Ffizz%2Fbuzz.html