前端设计模式——备忘录模式

// Originatorclass Editor {  constructor() {    this.content = "";  }  type(words) {    this.content += words;  }  save() {    return new EditorMemento(this.content);  }  restore(memento) {    this.content = memento.getContent();  }}// Mementoclass EditorMemento {  constructor(content) {    this.content = content;  }  getContent() {    return this.content;  }}// Caretakerclass History {  constructor() {    this.states = [];  }  push(state) {    this.states.push(state);  }  pop() {    return this.states.pop();  }}// Usageconst editor = new Editor();const history = new History();// 编辑器输入内容editor.type("Hello, ");editor.type("World!");// 将当前状态保存到备忘录中，并将备忘录添加到历史记录中history.push(editor.save());// 继续编辑器输入内容editor.type(" How are you today?");// 输出当前编辑器内容console.log(editor.content); // "Hello, World! How are you today?"// 从历史记录中恢复上一个状态editor.restore(history.pop());// 输出恢复的编辑器内容console.log(editor.content); // "Hello, World!"