js 创建正则对象

const regex = /pattern/flags;

// 匹配所有以字母 'a' 开头的单词
const regex = /\b[aA]\w*\b/g;

// 测试字符串
const str = "Apple apricot banana Avocado";

// 使用正则表达式进行匹配
const matches = str.match(regex);
console.log(matches); // 输出: ["Apple", "apricot", "Avocado"]

const regex = new RegExp('pattern', 'flags');

// 动态创建一个匹配邮箱的正则表达式
const emailPattern = "^\\w+([.-]?\\w+)*@\\w+([.-]?\\w+)*(\\.\\w{2,3})+$";
const emailRegex = new RegExp(emailPattern, "i");

// 测试邮箱
const emails = [
  "example@example.com",
  "Invalid-email@.com",
  "user.name+tag+sorting@example.co.uk"
];

emails.forEach(email => {
  if (emailRegex.test(email)) {
    console.log(`${email} 是有效的邮箱地址`);
  } else {
    console.log(`${email} 不是有效的邮箱地址`);
  }
});

// 错误示例
const wrongRegex = new RegExp("\\");

// 正确示例
const correctRegex = new RegExp("\\");

const regex = /\d/g;
const str1 = "123";
const str2 = "456";

console.log(regex.test(str1)); // true
console.log(regex.test(str2)); // false，因为 lastIndex 已经被更新

regex.lastIndex = 0; // 重置 lastIndex

const regex = /hello/i;
console.log(regex.test("Hello World")); // true