The only reason to use typeof foo === "undefined" is when foo is a
global identifier that might not have been declared at all, so it
might raise a ReferenceError if evaluated. For a variable declared
with const or let or import, a function argument, or a complex
expression, simply foo === undefined is equivalent.
Some of these conditions have become impossible and can be removed
entirely, and some can be replaced more idiomatically with default
parameters (note that JavaScript does not share the Python misfeature
of evaluating the default parameter at function declaration time).
Signed-off-by: Anders Kaseorg <anders@zulip.com>
This mainly extracts a new module called
browser_history. It has much fewer dependencies
than hashchange.js, so any modules that just
need the smaller API from browser_history now
have fewer transitive dependencies.
Here are some details:
* Move is_overlay_hash to hash_util.
* Rename hashchange.update_browser_history to
brower_history.update
* Move go_to_location verbatim.
* Remove unused argument for exit_overlay.
* Introduce helper functions:
* old_hash()
* set_hash_before_overlay()
* save_old_hash()
We now have 100% line coverage on the extracted
code.
Anders Kaseorg
Steve Howell