The CSS is now served as an external file instead of being injected.
This was done to improve performance. Ideally we would come to a middle
ground between this and the former behaviour by injecting only the CSS
that was required for the initial page load, then lazily loading the
rest. However that change would be more complex. The hope was that
making all CSS external would at least be a slight improvement.
Performance metrics were collected before and after this change to
determine whether this change actually helped. The metrics collected
were the timing events provided by Chrome DevTools:
* DOM Content Loaded (DCL) [1]
* Load (L) [2]
* First Paint (FP) [3]
* First Contentful Paint (FCP) [3]
* First Meaningful Paint (FMP) [3]
Here are the results (units in milliseconds):
Injected CSS:
| Run | DCL | L | FP | FCP | FMP |
| :--- | ---: | ---: | ---: | ---: | ---: |
| 1 | 1569.45 | 1570.97 | 1700.36 | 1700.36 | 1700.36 |
| 2 | 1517.37 | 1518.84 | 1630.98 | 1630.98 | 1630.98 |
| 3 | 1603.71 | 1605.31 | 1712.56 | 1712.56 | 1712.56 |
| 4 | 1522.15 | 1523.72 | 1629.3 | 1629.3 | 1629.3 |
| **Min** | 1517.37 | 1518.84 | 1629.3 | 1629.3 | 1629.3 |
| **Max** | 1603.71 | 1605.31 | 1712.56 | 1712.56 | 1712.56 |
| **Mean** | 1553.17 | 1554.71 | 1668.3 | 1668.3 | 1668.3 |
| **Std. dev.** | 33.41 | 33.43 | 38.16 | 38.16 | 38.16 |
External CSS:
| Run | DCL | L | FP | FCP | FMP |
| :--- | ---: | ---: | ---: | ---: | ---: |
| 1 | 1595.4 | 1598.91 | 284.97 | 1712.86 | 1712.86 |
| 2 | 1537.55 | 1538.99 | 199.38 | 1633.5 | 1633.5 |
| 3 | 1571.28 | 1572.74 | 268.65 | 1677.03 | 1677.03 |
| 4 | 1510.98 | 1512.33 | 206.72 | 1607.03 | 1607.03 |
| **Min** | 1510.98 | 1512.33 | 199.38 | 1607.03 | 1607.03 |
| **Max** | 1595.4 | 1598.91 | 284.97 | 1712.86 | 1712.86 |
| **Mean** | 1553.8025 | 1555.7425 | 239.93 | 1657.605 | 1657.605 |
| **Std. dev.** | 29.5375 | 30.0825 | 36.88 | 37.34 | 37.34 |
Unfortunately, using an external CSS file made no discernible improvement
to the overall page load time. DCM and L were practically identical, and
FCP and FMP were marginally better (well within error margins).
However, the first paint time was _dramatically_ improved. This change
seems worthwhile for the first paint time improvement alone. It also
allows us to delete some code and remove a dependency.
The old `css.js` module included two third-party CSS files as well, so
those have been imported into the main Sass file. This was easier than
bundling them in the gulpfile.
The resulting CSS bundle needs to be served from the root because we're
using a few `@include` rules that make this assumption. We could move
this under `/css/` if desired, but we'd need to update each of these
`@include` rules.
Relates to #6646
[1]: https://developer.mozilla.org/en-US/docs/Web/Events/DOMContentLoaded
[2]: https://developer.mozilla.org/en-US/docs/Web/Events/load
[3]: https://developers.google.com/web/fundamentals/performance/user-centric-performance-metrics
Set the minimum browser version supported in the extension manifest.
Currently we only ship the extension on Chrome and Firefox, so the
minimum version has been set for those two browsers.
Relates to #6805
* Add React and Redux DevTools
* Conditionally load react-devtools
* Add start:dev npm script to run the app with devtools
Co-Authored-By: Mark Stacey <markjstacey@gmail.com>
The `disc` gulp command no longer works. I wasn't able to fix this
easily, so instead it has been removed. We can probably find something
better to replace it with.
The flat tests also rely upon these transformations, yet invoke
browserify from the command line rather than using the gulpfile. The
transformations have been specified on the command line for those
instead.
Of course it's not ideal to have the same transformations listed in two
different places, but the plan is to delete the flat tests soon anyway,
so this should suffice until then.
Closes#4538
There is currently a bug in chrome that prevents reading source maps
from a local file [0]. This was preventing Chrome DevTools from using
our JavaScript source maps, where were saved as `.map` files. To work
around this problem the source maps are now generated inline, which
seems to work fine.
The only other browser I tested this with was Firefox, which works both
before and after this change.
[0]: https://bugs.chromium.org/p/chromium/issues/detail?id=931675
* eslint: Check for unused function arguments
* eslint: Ignore unused '_' in argument list
Also allow any number of '_' e.g., '__' or '___' which is to be used sparingly
* Remove and rename unused arguments
