字符串重复n 次，n可能是负数

0) {//num>0 之后再num-- 哦 strRepeated+= str; } return strRepeated; } repeatStringNumTimes("abc", 2);"> 0) {//num>0 之后再num-- 哦 strRepeated+= str; } return strRepeated; } repeatStringNumTimes("abc", 2);"> 0) {//num>0 之后再num-- 哦 strRepeated+= str; } return strRepeated; } repeatStringNumTimes("abc", 2);">

//str.repeat()
str = n>0?str.repeat(n):''

//other way
function repeatStringNumTimes(str, num) {
  //if(num< 0)return ""
  let strRepeated= '';
  while(num-- > 0) {//num>0 之后再num-- 哦
    strRepeated+= str;
  }
  return strRepeated;
}

repeatStringNumTimes("abc", 2);