JavaScript策略模式与函数替换技巧

const validationRules = {

  required: (value) => value !== '' && value !== null && value !== undefined,

  email: (value) => /\S+@\S+\.\S+/.test(value),

  minLength: (value, len) => value.length >= len,

};

function validate(input, rule, ...args) {

  return validationRules[rule] ? validationRules[rule](input, ...args) : false;

}

// 使用

validate('hello@163.com', 'email'); // true

validate('hi', 'minLength', 5); // false

let apiCall = function(url, data) {

  // 开发环境模拟返回

  console.log(`[Mock] POST ${url}`, data);

  return Promise.resolve({ success: true });

};

// 生产环境替换成真实请求

if (process.env.NODE_ENV === 'production') {

  apiCall = function(url, data) {

    return fetch(url, {

      method: 'POST',

      body: JSON.stringify(data)

    });

  };

}

const notifyStrategy = {

  email: (msg) => console.log('发送邮件:', msg),

  sms: (msg) => console.log('发送短信:', msg),

  push: (msg) => console.log('推送消息:', msg),

};

let notify = notifyStrategy.email; // 默认方式

// 根据用户偏好切换

function setNotificationMethod(type) {

  if (notifyStrategy[type]) {

    notify = notifyStrategy[type];

  }

}

// 调用统一接口

setNotificationMethod('sms');

notify('订单已提交'); // 输出：发送短信: 订单已提交