我需要帮助获取字符串的前n个字符，直到数字字符开始

function getSubstringUntilNumber(str, n) {
  let result = "";
  for (let i = 0; i < str.length; i++) {
    if (isNaN(str[i]) && result.length < n) {
      result += str[i];
    } else {
      break;
    }
  }
  return result;
}

// 示例用法
const originalString = "Hello123World";
const n = 5;
const substring = getSubstringUntilNumber(originalString, n);
console.log(substring); // Output: "Hello"