Longest Common Prefix

let longestCommonPrefix = function(strs) {

    if (!strs.length) return '';

    let index = 0, curr = '';
    for (;;)
    {
        for (let i = 0; i < strs.length; i++) {
            if (strs[i].length <= index) {
                return strs[0].substring(0, index); //?
            }
            if (curr === '') curr = strs[i][index];
            if (curr !== strs[i][index]) {
                return strs[0].substring(0, index);
            }
            if (i === strs.length - 1) {
                curr = '';
                index++
            }
        }
    }

    return '';
};