JavaScript 常用设计模式

prtyaa 2023-12-26 17:34:51  67492

分类专栏：资讯

单例模式

class AppState {
  counter = 0;
  private static instanceRef: AppState;
  private constructor() {}
  static getInstance(): AppState {
    if (AppState.instanceRef === undefined) {
      AppState.instanceRef = new AppState();
    }
    return AppState.instanceRef;
  }
}

const state1 = AppState.getInstance();
const state2 = AppState.getInstance();

state1.counter++;
state1.counter++;
state2.counter++;
state2.counter++;

console.log(state1.counter) // 4
console.log(state2.counter) // 4

工厂模式

type EmployeeType = FullTime | PartTime | Temporary | Contractor;
type EmployeeTypeStr = 'fulltime' | 'parttime' | 'temporary' | 'contractor';

class Factory {
  createEmployee(type: EmployeeTypeStr): EmployeeType {
    let employee: EmployeeType;
    switch (type) {
      case 'fulltime':
        employee = new FullTime();
        break;
      case 'parttime':
        employee = new PartTime();
        break;
      case 'temporary':
        employee = new Temporary();
        break;
      case 'contractor':
        employee = new Contractor();
        break;
    }
    employee.type = type;
    employee.say = function() {
      console.log(`${this.type} rate: ${this.hourly}/hour`);
    };
    return employee;
  }
}

interface Employee {
  say: Function;
  type: string;
  hourly: string;
}

class FullTime {
  say: Function = () => {};
  type: string = '';
  hourly: string;
  constructor() {
    this.hourly = '$12';
  }
}

class PartTime {
  say: Function = () => {};
  type: string = '';
  hourly: string;
  constructor() {
    this.hourly = '$11';
  }
}

class Temporary {
  //say?: Function;
  say: Function = () => {};
  type: string = '';
  hourly: string;
  constructor() {
    this.hourly = '$10';
  }
}

class Contractor {
  say: Function = () => {};
  type: string = '';
  hourly: string;
  constructor() {
    this.hourly = '$15';
  }
}

const employees: EmployeeType[] = [];
const factory = new Factory();

employees.push(factory.createEmployee('fulltime'));
employees.push(factory.createEmployee('parttime'));
employees.push(factory.createEmployee('temporary'));
employees.push(factory.createEmployee('contractor'));

employees.forEach((employee) => {
  employee.say();
})

/*
fulltime rate: $12/hour
parttime rate: $11/hour
temporary rate: $10/hour
contractor rate: $15/hour
*/

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JavaScript 常用设计模式

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