Javascript string comparison fails when comparing unicode characters

Unlike what some other people here have said, this has nothing to do with encodings. Rather, your two strings use different code points to render the same visual characters.

To solve this correctly, you need to perform Unicode normalization on the two strings before comparing them. Unforunately, JavaScript doesn't have this functionality built in. Here is a JavaScript library that can perform the normalization for you: https://github.com/walling/unorm

The JavaScript equality operator == will appear to be failing under the following circumstances. In all cases it is programmer error. Not a bug in JavaScript.

1. The two strings do not contain the same number and sequence of characters.

2. There is whitespace or newlines before, within or after one string. Use a trim() operator on both and look closely at both strings.

3. Surprise typecasting. The programmer is comparing datatypes that are incompatible.

4. There are unicode characters which look identical to other unicode characters but in fact are different unicode characters.

UTF-8 is a complex thing. The charset has two different codes for characters such as á, é etc. As you already see in the URL encoded version, the HEX bytes of which the character is made differ for both versions.

See this answer for more information.