Leetcode --- longest public prefix

Title Description

• Write a function to find the longest common prefix in the string array .
• If no common prefix exists , Returns an empty string “”.
• Example 1：
• Input ：strs = [“flower”,“flow”,“flight”]
• Output ：“fl”
• Example 2：
• Input ：strs = [“dog”,“racecar”,“car”]
• Output ：""
• explain ： Input does not have a common prefix .

How to solve the problem

    var longestCommonPrefix = function(strs) {
     
        if(strs.length===0){
     
            return '';
        }
        let res=strs[0];
        for(let i=0;i<strs.length;i++){
     
            let j=0;
            for(;j<res.length&&j<strs[i].length;j++){
     
                if(res[j]!=strs[i][j]){
     
                    break;
                }
            }
            res=res.substr(0,j);
            if(res===""){
     
                return res;
            }
        }
        return res;
    };