Find Smallest Letter Greater Than Target

LeetCode題目: 744. Find Smallest Letter Greater Than Target

My solution:

/**
 * @param {character[]} letters
 * @param {character} target
 * @return {character}
 */
let nextGreatestLetter = (letters, target) => {
    const targetCharCode = target.charCodeAt();
    for(let i=0; i<letters.length; i++){
        if(letters[i].charCodeAt() > targetCharCode) return letters[i];
    }
    return letters[0];
};