Q:

Cannot read property 'querySelectorAll' of undefined

 
I receive this error on console Uncaught TypeError: Cannot read property 'querySelectorAll' of undefined ionic.bundle.js:2800 when i go from other view using ionic, but I don't know that is means, and how to solve it

A:

Disclaimer: I do not have much experience with ionic, this is based upon my experience with general JavaScript.
What your error likely comes from is that a specific element that the code relies on, which can't be found when you switch views. I gathered this from querySelectorAll being a property of an Element. It is used to get an child element by the provided CSS Selector. It is frequently used as document.querySelectorAll to get any element on the page that matches the query.
From what you're given us, it appears that your code(or the library internally) is trying to use querySelectorAll on an element in a specific view every time the view changes, regardless of whether it's the view that contains the element or not. This inevitably resulting in the specific element being undefined, and hence not having the querySelectorAll property. Here's some mock code that'd result in roughly the same problem as you have.
# This would be run every time the view changes. 
let myElement = document.querySelectorAll('#element-in-different-view');
myElement === undefined; // true

myElement.querySelectorAll('#foo');
// undefined is not an Element, and as such doesn't have the property `querySelectorAll`

Important Note: As a community, we can provide you with more specific answers if you include the full traceback you get and a mvce.

