Bootstrap Tour实现报错：TypeError: Cannot read property 'onNext' of undefined

Hey there, let's figure out why your Bootstrap Tour is throwing that frustrating error when you click "Next". That Cannot read property 'onNext' of undefined message almost always boils down to a problem with how your tour steps are set up—here are the most common fixes to get your tour working again:

• Check for undefined entries in your steps array
  This is the #1 culprit. If your steps array has an accidental empty entry (like an extra comma between steps), it creates an undefined item. When the tour tries to load that undefined step next, it can't access the onNext property (since there's no step object to begin with).
  Example of a broken step array:

  var tour = new Tour({
    steps: [
      { element: "#profile-menu", title: "Your Profile" },
      // Oops—extra comma here creates an undefined step
      ,
      { element: "#settings-button", title: "Adjust Settings" }
    ]
  });
  

  Fix: Remove any stray commas and make sure every entry in the array is a complete step object.

• Make sure every step has required properties
  Bootstrap Tour needs each step to have either an element (targeting an on-page element) or a path (for navigating to a new URL). If a step is missing both, or if you've dynamically modified the steps array and accidentally deleted a step object, the tour will hit an undefined step when moving forward.
  Double-check that you haven't skipped any step definitions or accidentally removed a step from the array before starting the tour.

• Validate your tour initialization flow
  It's easy to forget to initialize the tour before starting it. If you call tour.start() without first running tour.init(), the tour might not properly parse your steps array, leading to undefined step references.
  Stick to this correct order:

  // Define your tour
  var tour = new Tour({
    steps: [/* your valid steps here */]
  });
  
  // Initialize first, then start
  tour.init();
  tour.start();
  

• Debug with a console log
  To confirm the issue, add a console log right before starting the tour to inspect your steps array:

  console.log('Tour steps:', tour.steps);
  

  Open your browser's dev tools (F12) and check the console—if any entry shows up as undefined, that's exactly where your problem is.

内容的提问来源于stack exchange，提问作者Kevin Ceaser