In Sketch, how can I easily collapse pages in the layer list on the left side of the screen?
Are you talking about the possibility to collapse every Artboard in a Sketch page?
If so, you can select
Layer List →
Collapse All Groups
In Sketch 57 there is no default shortcut for that option but you can easily create one thanks to macOS.
To create an application specific shortcut on macOS 10.14 :
System Preferences →
Shortcuts (the tab pane) → and select
App Shortcuts (left panel).
Then you can add any application (Sketch would probably be your choice here!) thanks to the + icon on the bottom of the window. There you can select Sketch using the dropdown menu that you are now facing.
This is where it gets a little bit counterintuitive (in my opinion) because the
Title you will give to your new shortcut is the actual steps the program is going to follow to do your task.
If I want to create a shortcut to
Collapse All Groups, I'll have to call my custom shortcut like this :
View->Layer List->Collapse All Groups
These are the steps you would take to make this happen. You can then add any shortcut (not already in use) to make it happen while using Sketch. In my example, I'm using ⌘⇧C. When added, you are now able to Collapse everything thanks to your brand new shortcut!