最长公共前缀

// 最长公共子前缀
  var testStrList = ['abcd','abc','abcdmg','aggg']
  function longCommon1(list){
    let first = list[0]
    for(let i = 0;i < first.length;i++){
      let str = first.charAt(i)
      for(let j = 1;j<list.length;j++){
        if(i == list[j].length || str !== list[j].charAt(i)){
          return first.substring(0, i)
        }
      }
    }
  }
  function longCommon(list) {
    if(list.length == 0){
      return ''
    }
    let result = list[0]
    for(let i = 0; i < list.length; i++) {        
      while(list[i].indexOf(result) != 0) { 
          console.log('1',list[i],result)       
        result = result.substring(0, result.length - 1);
        console.log('2',list[i],result)              
        if(result.length == 0) {
          return "";            
        }        
      }    
    }    
    return result;
  }
  console.log(longCommon1(testStrList))