Please note that these changes were done automatically, using `gulp lint --fix`.
Given that the major version number was increased, there's a fair number of (primarily whitespace) changes; please see https://prettier.io/blog/2020/03/21/2.0.0.html
In order to reduce the size of these changes somewhat, this patch maintains the old "arrowParens" style for now (once mozilla-central updates Prettier we can simply choose the same formatting, assuming it will differ here).
This patch makes the follow changes:
- Remove no longer necessary inline `// eslint-disable-...` comments.
- Fix `// eslint-disable-...` comments that Prettier moved down, thus causing new linting errors.
- Concatenate strings which now fit on just one line.
- Fix comments that are now too long.
- Finally, and most importantly, adjust comments that Prettier moved down, since the new positions often is confusing or outright wrong.
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.)
In many cases in the code you don't actually care about the index itself, but rather just want to know if something exists in a String/Array or if a String starts in a particular way. With modern JavaScript functionality, it's thus possible to remove a number of existing `indexOf` cases.
http://eslint.org/docs/rules/comma-danglehttp://eslint.org/docs/rules/object-curly-spacing
*Please note:* This patch was created automatically, using the ESLint `--fix` command line option. In a couple of places this caused lines to become too long, and I've fixed those manually; please refer to the interdiff below for the only hand-edits in this patch.
```diff
diff --git a/gulpfile.js b/gulpfile.js
index d18b9c58..7d47fd8d 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -1247,7 +1247,8 @@ gulp.task('gh-pages-git', ['gh-pages-prepare', 'wintersmith'], function () {
var reason = process.env['PDFJS_UPDATE_REASON'];
safeSpawnSync('git', ['init'], { cwd: GH_PAGES_DIR, });
- safeSpawnSync('git', ['remote', 'add', 'origin', REPO], { cwd: GH_PAGES_DIR, });
+ safeSpawnSync('git', ['remote', 'add', 'origin', REPO],
+ { cwd: GH_PAGES_DIR, });
safeSpawnSync('git', ['add', '-A'], { cwd: GH_PAGES_DIR, });
safeSpawnSync('git', [
'commit', '-am', 'gh-pages site created via gulpfile.js script',
```
*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/
Features / bug fixes in the preprocessor:
- Add word boundary after regex for preprocessor token matching.
Previously, when you mistakenly used "#ifdef" instead of "#if", the
line would be parsed as a preprocessor directive (because "#ifdef"
starts with "#if"), but without condition (because "def" does not
start with a space). Consequently, the condition would always be false
and anything between "#ifdef" and "#endif" would not be included.
- Add validation and error reporting everywhere, to aid debugging.
- Support nested comments (by accounting for the whole stack of
conditions, instead of only the current one).
- Add #elif preprocessor command. Could be used as follows:
//#if !FEATURE_ENABLED
//#error FEATURE_ENABLED must be set
//#endif
- Add #error preprocessor command.
- Add end-of-line word boundary after "-->" in the comment trimmer.
Otherwise the pattern would also match "-->" in the middle of a line,
and incorrectly convert something like "while(i-->0)" to "while(i0)".
Code health:
- Add unit tests for the preprocessor (run external/builder/test.js).
- Fix broken link to MDN (resolved to DXR).
- Refactor to use STATE_* names instead of magic numbers (the original
meaning of the numbers is preserved, with one exception).
- State 3 has been split in two states, to distinguish between being in
an #if and #else. This is needed to ensure that #else cannot be
started without an #if.
It took a while to figure out why adding comments in worker_loader.js
caused the build to fail, because getWorkerSrcFiles did not print an
error message when it failed to parse the file. These issues have been
resolved as follows:
- Leading comments are stripped.
- The trailing comma is removed from the array.
- Errors are detected and useful error messages are printed.
There is no need to have a copy of ShellJS in the repository as it is also available on NPM. The NPM version is also much newer. This way we do not have to update this anymore and let NPM do that automatically.
