# Page Routing

The framework manages all the routes to pages of a Mini Program.

# Page Stack

The framework maintains all the existing pages via stacks. When a route is switched, the page stack reacts as follows:

Routing	Reaction on the Page Stack
Initialization	The new page is pushed onto the stack.
Opening a new page	The new page is pushed onto the stack.
Page redirection	The current page is popped out of the stack, and the new page is pushed onto the stack.
Page return	Pages are successively popped out of the stack until the destination return page is displayed.
Tab switching	All the pages are popped out of the stack, and only the new tab page is retained.
Reloading	All the pages are popped out of the stack, and only the new page is retained.

Developers can obtain the current page stack by using the getCurrentPages() function.

# Routing

The following shows how page routing is triggered and the lifecycle functions for pages.

Routing	Trigger Condition	Source Page	Routed-To Page
Initialization	A page of the Mini Program is opened for the first time.		onLoad, onShow
Opening a new page	The API wx.navigateTo is called. The component `<navigator open-type="navigateTo"/>` is used.	onHide	onLoad, onShow
Page redirection	The API wx.redirectTo is called. The component `<navigator open-type="redirectTo"/>` is used.	onUnload	onLoad, onShow
Page return	The API wx.navigateBack is called. The component `<navigator open-type="navigateBack">` is used. The user taps the return button on the top left.	onUnload	onShow
Tab switching	The API wx.switchTab is called. The component `<navigator open-type="switchTab"/>` is used. The user switches between tabs.		For details, refer to the following table.
Restart	The API wx.reLaunch is called. The component `<navigator open-type="reLaunch"/>` is used.	onUnload	onLoad, onShow

Lifecycle functions corresponding to tab switching (in the following example, pages A and B are Tabbar pages, page C is obtained after page A is opened, and page D is obtained after page C is opened):

Current Page	Routed-To Page	Triggered Lifecycle Function (In Order)
A	A	Nothing happend
A	B	A.onHide(), B.onLoad(), B.onShow()
A	B (Opened again)	A.onHide(), B.onShow()
C	A	C.onUnload(), A.onShow()
C	B	C.onUnload(), B.onLoad(), B.onShow()
D	B	D.onUnload(), C.onUnload(), B.onLoad(), B.onShow()
D (Entered due to redirection)	A	D.onUnload(), A.onLoad(), A.onShow()
D (Entered due to redirection)	B	D.onUnload(), B.onLoad(), B.onShow()

Tips:

navigateTo and redirectTo can be used to open non-tabBar pages only.
switchTab can be used to open tabBar pages only.
reLaunch can be used to open any pages.
The tabBar on the bottom of a page is determined by the page. In other words, tabBar is displayed on the bottom of all pages defined as tabBar.
Parameters used to call page routing can be obtained via onLoad in the destination page.