Implement undo redo document history system

Daily question

Medium

This question is a daily question and will count towards your daily streak.

In a collaborative document editor, you need to implement an undo/redo system that tracks changes efficiently. What's missing in this implementation?

State managementData structures

1class DocumentHistory {
  constructor(initialContent = '') {
      this.undoStack = [{ content: initialContent, timestamp: Date.now() }];
      this.redoStack = [];
      this.currentContent = initialContent;
  }
7
  recordChange(newContent) {
      // Missing implementation
      _______________
  }
12
  undo() {
      if (this.undoStack.length <= 1) return this.currentContent;
      
      const current = this.undoStack.pop();
      this.redoStack.push(current);
      const previous = this.undoStack[this.undoStack.length - 1];
      this.currentContent = previous.content;
      
      return this.currentContent;
  }
23
  redo() {
      if (this.redoStack.length === 0) return this.currentContent;
      
      const next = this.redoStack.pop();
      this.undoStack.push(next);
      this.currentContent = next.content;
      
      return this.currentContent;
  }
33}

This question is a daily question and will count towards your daily streak.

In a collaborative document editor, you need to implement an undo/redo system that tracks changes efficiently. What's missing in this implementation?

Hint