js 实例化正则

// 匹配所有数字
const regexLiteral = /\d+/g;

// 使用正则表达式
const str = "There are 123 apples and 456 oranges.";
const matches = str.match(regexLiteral);
console.log(matches); // 输出: ["123", "456"]

// 动态创建正则表达式
const pattern = "\\d+"; // 注意在字符串中反斜杠需要转义
const flags = "g";
const regexConstructor = new RegExp(pattern, flags);

// 使用正则表达式
const str = "There are 123 apples and 456 oranges.";
const matches = str.match(regexConstructor);
console.log(matches); // 输出: ["123", "456"]

// 使用字面量方式实例化正则表达式
const emailRegex = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;

// 测试邮箱地址
const emails = ["test@example.com", "invalid-email@", "user.name+tag+sorting@example.com"];
emails.forEach(email => {
  if (emailRegex.test(email)) {
    console.log(`${email} is a valid email address.`);
  } else {
    console.log(`${email} is not a valid email address.`);
  }
});