javascript - Syntax error when trying to test for empty string -

in javascript, trying simple task of testing , returning longest of 2 words. if words empty return should "empty string". keep getting syntax error when testing empty string or elseif statement. using (!word1) , (!word2) because understanding in javascript boolean statement , should false. please tell me going wrong:

function longest(word1, word2) {  if (word1.length >= word2.length) {      return (word1);  } else {      return (word2);  } else if (!word1) || (!word2) {      return "an empty string";  }  }  console.log(longest('hi')); 

if conditions should surrounded 1 pair of parentheses.

change else if (!word1) || (!word2) else if (!word1 || !word2).