신규 아이디 추천

function solution(new_id) {
    var answer = "";
    
    const removeRegex = /[^0-9|a-z|\_\-\.]/g;
    const continueRegex = /\.{2,}/g;
    const startEndRegex = /^[\.]|[\.]$/g;
    const endRegex = /[\.]$/g;
    
    answer = new_id.toLowerCase().replace(removeRegex, "").replace(continueRegex, ".").replace(startEndRegex, "");
    
    if(answer.length === 0) answer = "a";
    if(answer.length > 15) {
        answer = answer.slice(0, 15).replace(endRegex, "");
    }
    while(answer.length < 3){
        answer += answer.slice(-1);        
    }
    
    return answer;
}