Why does my header and add-to-cart button disappear randomly?

Topic summary

A user experienced intermittent disappearance of their site header and add-to-cart buttons on published pages (not in staging). The issue was traced to a JavaScript conflict between two jQuery versions:

  • The Palo Alto theme loads jQuery 3.5.1 with a throttle plugin
  • The PreOrder Now app loads its own jQuery 3.4.1
  • During a brief moment when the app’s jQuery takes control before running noConflict mode, the theme’s throttle function becomes undefined, causing errors

Proposed solutions:

  1. Prevent the app from loading its own jQuery by adding np.shop.never_load_jquery = true; before the </head> tag
  2. Delay app execution by adding defer="defer" to the app’s script tag
  3. Combine both approaches if necessary

Resolution: The original poster switched to a different app due to time constraints before launch, though they acknowledged the technical fix for future reference.

A secondary participant had a different issue (disappearing horizontal menu) which was resolved by shortening menu item titles to prevent overflow triggering the mobile hamburger menu.

Summarized with AI on November 11. AI used: claude-sonnet-4-5-20250929.

I don’t think that is the problem, seems like if it was in the CSS it would never be viewable, but the problem is random. It appears whenever the issue persist, I see a $.throttle is not a function type error.