根据长度拆分并添加字符串

function splitAndAddString(str, n) {
  if (str.length <= n) {
    return str;
  }

  let result = "";
  for (let i = 0; i < str.length; i += n) {
    result += str.substr(i, n);
    result += " "; // 添加空格分隔符
  }

  return result.trim(); // 去除首尾空格
}

// 示例用法
const originalString = "根据长度拆分并添加字符串";
const splitLength = 4;
const modifiedString = splitAndAddString(originalString, splitLength);
console.log(modifiedString);