*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/
Move the `Preferences` initialization/fetching code to the top of `PDFViewerApplication.initialize`, to enable using them when initializing e.g. the viewer components
Ideally we'd remove the 'localized' event from the `eventBus`, but for backwards compatibility we keep it in `GENERIC` builds.
Note that while we want to ensure that the direction attribute of the HTML is updated as soon as the `localized` Promise is resolved, we purposely wait until the viewer has been initialized to ensure that the 'localized' event will always be dispatched.
With `bindEvents()` now being called after the viewer has been initialized, we no longer need to have `PDFViewerApplication.initialized` checks in the event handler functions.
Furthermore by moving the `window.addEventListener`s to a helper method, `PDFViewerApplication.initialized` checks are no longer necessary in the event handlers, hence we thus address part of issue 7797 here as well.
Note that in quick testing using `console.time/timeEnd`, both locally and with the Firefox addon, the total run time of the *entire* `PDFViewerApplication.initialize` function does not seem to change with this patch.
This patch refactors the `CropBox` code to combine fetching and
validation code in a getter, like we already did for the `MediaBox`
property. Combined with variable name changes, this improves readability
of the code and makes the `view` getter simpler as well.
I've not actually, thus far, come across a PDF file that this patch fixes. However, given the string of recent patches that has fixed issues with indirect objects in arrays, I think that it makes sense to proactively avoid any issues in this code.
I just realized that none of our current unit-tests cover this particular part of the Page Label parsing code, hence this patch adjusts an existing test PDF to include a "St" entry in the Page Label dictionary.
This patch avoids the creation of extra arrays when initializing an
array with default (zero) values. Doing this additionally makes the code
more readable by allocating enough space for the number of color
components.
It seems that for normal web pages, at least in Firefox, the keyboard shortcuts <kbd>Ctrl</kbd> + <kbd>Up</kbd>/<kbd>Down</kbd> are functionally equivalent to <kbd>Home</kbd>/<kbd>End</kbd>. This is obviously an edge-case, but can be easily implemented by using the same logic as we do for <kbd>Home</kbd>/<kbd>End</kbd>.
Fixes 7852.
*Please note:* I'm finding it slightly difficult to interpret issue 7852, and bug 1285719, since among other things: the title includes the word "reverse" with no other mention of it, and the STR makes reference to print preview which doesn't seem applicable to the PDF viewer.
However, compared to regular web pages in Firefox, I think the behavior of this patch makes sense here.
Jonas Jenwald
Tim van der Meij
Yury Delendik
Javier Infante