js 字符串补位

function padLeft(str, targetLength, padChar = '0') {
  while (str.length < targetLength) {
    str = padChar + str;
  }
  return str;
}

// 示例
console.log(padLeft('123', 5)); // 输出: "00123"
console.log(padLeft('123', 5, '*')); // 输出: "**123"

function padRight(str, targetLength, padChar = '0') {
  while (str.length < targetLength) {
    str = str + padChar;
  }
  return str;
}

// 示例
console.log(padRight('123', 5)); // 输出: "12300"
console.log(padRight('123', 5, '*')); // 输出: "123**"

const str = '123';

// 左补位
console.log(str.padStart(5, '0')); // 输出: "00123"
console.log(str.padStart(5, '*')); // 输出: "**123"

// 右补位
console.log(str.padEnd(5, '0')); // 输出: "12300"
console.log(str.padEnd(5, '*')); // 输出: "123**"

function padLeft(str, targetLength, padChar = '0') {
  str = str.toString();
  while (str.length < targetLength) {
    str = padChar + str;
  }
  return str;
}