[javascript] How to get the previous URL in JavaScript?

If anyone is coming from React-world, I ended up solving my use-case using a combination of history-library, useEffect and localStorage

When user selects new project:

  function selectProject(customer_id: string, project_id: string){
    const projectUrl = `/customer/${customer_id}/project/${project_id}`
    localStorage.setItem("selected-project", projectUrl)
    history.push(projectUrl)
  }

When user comes back from another website. If there's something in localStorage, send him there.

  useEffect(() => {
    const projectUrl = localStorage.getItem("selected-project")
    if (projectUrl) {
      history.push(projectUrl)
    }
  }, [history])

When user has exited a project, empty localStorage

  const selectProject = () => {
    localStorage.removeItem("selected-project")
    history.push("/")
  }