Palindrome FP Validator

palindrome.js

const isEmpty = word => word === "";
const isSingleChar = word => word.length === 1;
const isDoubleChar = word => word.length === 2;
const firstChar = word => word[0];        
const lastChar = word => word.slice(-1);
const isMatch = (a,b) => a === b;
const trimEnds = word =>  word.slice(1,-1);
const isEndsMatched = word => isEmpty(word) || isMatch(firstChar(word), lastChar(word))

const isPalindrome = word => {

    if(!isEndsMatched(word)) {
        return false;
    }
      
    if(isEmpty(word) || isSingleChar(word) || isDoubleChar(word)) { 
        return true;
    }
          
    return isPalindrome(trimEnds(word))     
}

console.log(isPalindrome("tenet")); // true
console.log(isPalindrome("tennis")); // false