Input: strs = ["flower", "flow", "flight"];
Output: "fl";

Input: strs = ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

const longestCommonPrefix = function(strs) {
  let result;
  let prefix = "";
  for (let i = 0; i < strs.length; i++) {
    result = strs.filter(str => str.slice(i, i + 1) === strs[0][i]);

    if (strs.length === result.length) {
      prefix += strs[0][i];
    } else {
      break;
    }
  }

  return prefix === "" ? "" : prefix;
};

const longestCommonPrefix = function(strs) {
  let prefix = strs[0];

  for (let i = 1; i < strs.length; i++) {
    while (strs[i].indexOf(prefix) !== 0) {
      prefix = prefix.substring(0, prefix.length - 1);
    }
  }

  return prefix;
};