If you use `await` inside a loop it makes the loop inherently serial.
If you omit the `await` however, the tasks will all start but the loop
will finish while the tasks are still being scheduled.
So, to make a set of tasks run in parallel but then have the
code block after the loop once all the tasks have been completed
you have to get an array of Promises (one for each iteration) and
then use `Promise.all()` to wait for those promises to be resolved.
Using `Array#map` is a convenient way to go from an array of inputs
to the require array of Promises.
This change is in preparation of the future async refactoring by Ray. It tries
to extract as many changes in boolean conditions as possible, in order to make
more evident identifying eventual logic bugs in the future work.
This proved already useful in at least one case.
BEWARE: this commit exposes an incoherency in the DB API, in which, depending
on the driver used, some functions can return null or undefined. This condition
will be externally fixed by the final commit in this series ("db/DB.js: prevent
DB layer from returning undefined"). Until that commit, the code base may have
some bugs.
This change extracts the grammar correction performed on the async branch,
anticipating them in a single commit. It cannot be folded with the previous
one, as it is not purely cosmetic.
This change is only cosmetic. Its aim is do make it easier to understand the
async changes that are going to be merged later on. It was extracted from the
original work from Ray Bellis.
To verify that nothing has changed, you can run the following command on each
file touched by this commit:
npm install uglify-es
diff --unified <(uglify-js --beautify bracketize <BEFORE.js>) <(uglify-js --beautify bracketize <AFTER.js>)
This is a complete script that does the same automatically (works from a
mercurial clone):
```bash
#!/usr/bin/env bash
set -eu
REVISION=<THIS_REVISION>
PARENT_REV=$(hg identify --rev "${REVISION}" --template '{p1rev}')
FILE_LIST=$(hg status --no-status --change ${REVISION})
UGLIFYJS="node_modules/uglify-es/bin/uglifyjs"
for FILE_NAME in ${FILE_LIST[@]}; do
echo "Checking ${FILE_NAME}"
diff --unified \
<("${UGLIFYJS}" --beautify bracketize <(hg cat --rev "${PARENT_REV}" "${FILE_NAME}")) \
<("${UGLIFYJS}" --beautify bracketize <(hg cat --rev "${REVISION}" "${FILE_NAME}"))
done
```
