create a browser history

Question

I believe you are very familiar about your browser you are currently visiting https://bigfrontend.dev with.

The common actions relating to history are:

1. new BrowserHistory() - when you open a new tab, it is set with an empty history
2. goBack() - go to last entry, notice the entries are kept so that forward() could get us back
3. forward() - go to next visited entry
4. visit() - when you enter a new address or click a link, this adds a new entry but truncate the entries which we could forward() to.

Say we start a new tab, this is the empty history.

[ ] 

Then visit url A, B, C in turn.

[ A, B, C]
        ↑

We are currently at C, we could goBack() to B, then to A

[ A, B, C]
  ↑          

forward() get us to B

[ A, B, C]
     ↑          

Now if we visit a new url D, since we are currently at B, C is truncated.

[ A, B, D]
        ↑

You are asked to implement a BrowserHistory class to mimic the behavior.

Code

class BrowserHistory {
  
  /**
   * @param {string} url
   * if url is set, it means new tab with url
   * otherwise, it is empty new tab
   */
  constructor(url) {

  }
  /**
   * @param { string } url
   */
  visit(url) {

  }
  
  /**
   * @return {string} current url
   */
  get current() {

  }
  
  // go to previous entry
  goBack() {

  }
  
  // go to next visited url
  forward() {

  }
}

Source

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