Copy and run, individually, the following lines of code in your console:
console.log( '#1:', 'mañana' === 'mañana' );
console.log( '#2:', 'mañana' === 'mañana' );
It logs true because the two words are the same characters.
It logs false because the encoding of characters and the character ñ contains( n and ̃ ) it's an issue with UTF8 encoding.