js查找最长字符串

function findLongestString(arr) {
    if (!Array.isArray(arr) || arr.length === 0) {
        return null;
    }
    let longest = arr[0];
    for (let i = 1; i < arr.length; i++) {
        if (arr[i].length > longest.length) {
            longest = arr[i];
        }
    }
    return longest;
}

// 示例用法
const strings = ["apple", "banana", "cherry", "date"];
const longestString = findLongestString(strings);
console.log(longestString); // 输出: "banana"