Note that Prettier, purposely, has only limited [configuration options](https://prettier.io/docs/en/options.html). The configuration file is based on [the one in `mozilla central`](https://searchfox.org/mozilla-central/source/.prettierrc) with just a few additions (to avoid future breakage if the defaults ever changes).
Prettier is being used for a couple of reasons:
- To be consistent with `mozilla-central`, where Prettier is already in use across the tree.
- To ensure a *consistent* coding style everywhere, which is automatically enforced during linting (since Prettier is used as an ESLint plugin). This thus ends "all" formatting disussions once and for all, removing the need for review comments on most stylistic matters.
Many ESLint options are now redundant, and I've tried my best to remove all the now unnecessary options (but I may have missed some).
Note also that since Prettier considers the `printWidth` option as a guide, rather than a hard rule, this patch resorts to a small hack in the ESLint config to ensure that *comments* won't become too long.
*Please note:* This patch is generated automatically, by appending the `--fix` argument to the ESLint call used in the `gulp lint` task. It will thus require some additional clean-up, which will be done in a *separate* commit.
(On a more personal note, I'll readily admit that some of the changes Prettier makes are *extremely* ugly. However, in the name of consistency we'll probably have to live with that.)
This patch ignores the recently added `disableOpenActionDestination` preference, since the latest PDF.js version found on the "Chrome Web Store" doesn't include it.
In a1cfa5f4d7, the textLayerMode
preference was introduced, to replace the disableTextLayer and
enhanceTextSelection preferences.
As a result, the text selection preference was no longer visible
in Chrome (because preferences are only rendered by default for
boolean preferences, not for enumerations).
This commit adds the necessary bits to
extensions/chromium/options/options.{html,js}
so that the textLayerMode preference can be changed again.
Also, migration logic has been added to move over preferences
from the old to the new names:
- In web/chromecom.js, the logic is added to translate
preferences that were set by an administrator (it is read-only,
so this layer is unavoidable).
- In extensions/chromium/options/migration.js, similar logic is
added, except in this case the preference storage is writable,
so this migration logic happens only once.
The "enhanced text selection" mode is still experimental, so it
has been marked as experimental to signal that there may be bugs.
The list of tasks that block promotion to stable is at #7584.
Add UI for the cursorToolOnLoad pref in the UI of the Chrome extension.
Add logic to migrate the enableHandToolOnLoad pref to cursorToolOnLoad.
For past values in the mutable extension storage area:
1. If enableHandToolOnLoad=true, save cursorToolOnLoad=1.
2. Remove enableHandToolOnLoad.
For the managed extension storage, which is immutable since it is based
on administrative policies, use the following logic:
1. If enableHandToolOnLoad=true and cursorToolOnLoad=0 (default).
set cursorToolOnLoad=0 and assume enableHandToolOnLoad=false.
2. As usual, managed preferences can (and will) be overridden by the user.
The first migration logic is in extensions/chromium/options/migration.js
and can be removed after a few months / less than many years.
The second migration logic is in web/chromecom.js, and should be kept
around for a long while (many years).
The need for this migration logic arises from the change by:
https://github.com/mozilla/pdf.js/pull/7635
*Please note that most of the necessary code adjustments were made in PR 7890.*
ESLint has a number of advantageous properties, compared to JSHint. Among those are:
- The ability to find subtle bugs, thanks to more rules (e.g. PR 7881).
- Much more customizable in general, and many rules allow fine-tuned behaviour rather than the just the on/off rules in JSHint.
- Many more rules that can help developers avoid bugs, and a lot of rules that can be used to enforce a consistent coding style. The latter should be particularily useful for new contributors (and reduce the amount of stylistic review comments necessary).
- The ability to easily specify exactly what rules to use/not to use, as opposed to JSHint which has a default set. *Note:* in future JSHint version some of the rules we depend on will be removed, according to warnings in http://jshint.com/docs/options/, so we wouldn't be able to update without losing lint coverage.
- More easily disable one, or more, rules temporarily. In JSHint this requires using a numeric code, which isn't very user friendly, whereas in ESLint the rule name is simply used instead.
By default there's no rules enabled in ESLint, but there are some default rule sets available. However, to prevent linting failures if we update ESLint in the future, it seemed easier to just explicitly specify what rules we want.
Obviously this makes the ESLint config file somewhat bigger than the old JSHint config file, but given how rarely that one has been updated over the years I don't think that matters too much.
I've tried, to the best of my ability, to ensure that we enable the same rules for ESLint that we had for JSHint. Furthermore, I've also enabled a number of rules that seemed to make sense, both to catch possible errors *and* various style guide violations.
Despite the ESLint README claiming that it's slower that JSHint, https://github.com/eslint/eslint#how-does-eslint-performance-compare-to-jshint, locally this patch actually reduces the runtime for `gulp` lint (by approximately 20-25%).
A couple of stylistic rules that would have been nice to enable, but where our code currently differs to much to make it feasible:
- `comma-dangle`, controls trailing commas in Objects and Arrays (among others).
- `object-curly-spacing`, controls spacing inside of Objects.
- `spaced-comment`, used to enforce spaces after `//` and `/*. (This is made difficult by the fact that there's still some usage of the old preprocessor left.)
Rules that I indend to look into possibly enabling in follow-ups, if it seems to make sense: `no-else-return`, `no-lonely-if`, `brace-style` with the `allowSingleLine` parameter removed.
Useful links:
- http://eslint.org/docs/user-guide/configuring
- http://eslint.org/docs/rules/
Use chrome.storage.sync to store preferences instead of
chrome.storage.local, to allow settings to be synchronized if the user
chooses to sign in in Chrome and enables synchronization of extension
preferences.
