Remove unused MemberExpression root identifiers #158
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In our codebase, I noticed that we had the following pattern that was
not getting properly cleaned up:
```js
const shapePropType = PropTypes.shape({
foo: PropTypes.string,
});
const ComponentA = () => <div />;
ComponentA.propTypes = {
foo: shapePropType.isRequired,
};
```
The notable thing here is that inside the propTypes assignment, a
MemberExpression is used instead of just an identifier. However, in our
visitor for collecting nested identifiers, we special-cased Identifiers
that have a MemberExpression parent to not be collected. This was to
prevent the `bar` portion of `foo.bar` from being collected. However, in
this case, we actually want the `foo` part of `foo.bar` to be collected
for possible additional cleanup, so we need to add a little more logic
to make this happen.
To solve this, I added a function that takes a path and traverses up the
tree until it finds the first non-MemberExpression, and then traverses
down the left side of that tree until it finds the root identifier. This
should be the `foo` in `foo.bar.baz`, for instance.
It seems likely that there is a better more built-in Babel way to do
this, but I was unable to find anything to point me in that direction so
I rolled my own.
lencioni
force-pushed
the
memberexpression
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| const somePropTypes = process.env.NODE_ENV !== "production" ? { | ||
| foo: PropTypes.string, | ||
| bar: PropTypes.number | ||
| } : {};; |
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Do you know where the ;; is coming from?
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Unfortunately no. I suspect it might be a bug in Babel, or maybe with the way we are doing the templating.
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OK thanks, @eps1lon might have found something.
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In our codebase, I noticed that we had the following pattern that was
not getting properly cleaned up:
The notable thing here is that inside the propTypes assignment, a
MemberExpression is used instead of just an identifier. However, in our
visitor for collecting nested identifiers, we special-cased Identifiers
that have a MemberExpression parent to not be collected. This was to
prevent the
barportion offoo.barfrom being collected. However, inthis case, we actually want the
foopart offoo.barto be collectedfor possible additional cleanup, so we need to add a little more logic
to make this happen.
To solve this, I added a function that takes a path and traverses up the
tree until it finds the first non-MemberExpression, and then traverses
down the left side of that tree until it finds the root identifier. This
should be the
fooinfoo.bar.baz, for instance.It seems likely that there is a better more built-in Babel way to do
this, but I was unable to find anything to point me in that direction so
I rolled my own.