Sourcemaps
Check out the source style.scss file. We're giving an element a fancy cursive
font on lines 4 and 5. And that's what makes the Dinosaurs text look so
awesome.
But if we inspect that element, it says the font is coming from styles.css
line 2. Dang it! The browser is looking at the final, processed file. And
that means that debugging CSS is going to be an absolute nightmare.
What I really want is the debugger to be smart enough to tell me that this
font is coming from our styles.scss file at line 4. Such mysterious magic
goodness exists, and it's called a sourcemap.
Using gulp-sourcemaps
Like with everything, this works via a plugin. Head back to the plugins page and search for gulp-sourcemaps. There's the one I want!
Step 1 is always the same - install with npm. So:
npm install gulp-sourcemaps --save-dev
Awesome! Next, copy the require statement and put that on top:
| var gulp = require('gulp'); | |
| var sass = require('gulp-sass'); | |
| var sourcemaps = require('gulp-sourcemaps'); | |
| // ... lines 4 - 12 |
This plugin is great. First, activate it before piping through any filters
that may change which line some code lives on. So, before the sass() line,
use pipe() with sourcemaps.init() inside. Then after all those filters
are done, pipe it again through sourcemaps.write('.'):
| // ... lines 1 - 4 | |
| gulp.task('default', function() { | |
| gulp.src('app/Resources/assets/sass/**/*.scss') | |
| .pipe(sourcemaps.init()) | |
| .pipe(sass()) | |
| .pipe(sourcemaps.write('.')) | |
| .pipe(gulp.dest('web/css')); | |
| }); |
Ok, let's try it! At the terminal, run gulp... and hope for the best!
gulp
Cool - no errors. And now, the generated styles.css has a neighboring
file: styles.css.map! That's what the . did - it told Gulp to put the
map file right in the same directory as styles.css, and the browser knows
to look there.
Time to refresh the page again. Inspect the element again. Now it says the
font comes from styles.scss on line 4. This is a huge deal guys. We can
do whatever weird processing we want and not worry about killing our debugging.
Sourcemaps Support
Of course, this all works because gulp-sourcemaps and gulp-sass work
together like super friends. If you look at the sourcemaps docs, they have
a link on their wiki to a list of all super-friend gulp plugins that play
nice with it. We'll use a couple of these later.
9 Comments
Congratulations !!! Post simple, objective, direct and functional. No more posts like this one, rare thing!
Whatever I do I can't make sourcemaps work as in the video.
Sourcemaps always gives me 'stdin' as style file, so when I inspect an element I see stdin and not source scss file.
Hey!
I don't remember seeing this problem originally, but I *can* see it now: the sourcemaps incorrectly thinks that the source of *some* selectors os stdin. For me, it looks like it works correctly for any source files that are .scss: the problem is only for source files that are true css files (e.g. bootstrap.css). Do you see the same thing? What I mean is, I can "Inspect Element" on a style that comes from an .scss file and it shows me the proper source. If I do the same for a style that comes originally from a CSS file, that's when I see the stdin.
Thanks!
I opened an issue to track this problem: https://github.com/knpunive...
Ok cool.
Ryan,
For me it's the other way around: everything works as excepted with *.css files but not with scss files. I suspect it works with less too, but I havent fully tested this. I say this because including bootstrap.css with scss files does show source bootstrap less files.
For example, when I comment .pipe(plugins.sass()) from addStyle function and load css files sourcemaps work as expected.
Strangely, as soon as I use scss files (with .pipe(plugins.sass()) and write style it switches to stdin. To clearify:
In style.scss:
.some-dino-class {}
.some-other-thingie {}
works.
main.css.map gives: {"version":3,"sources":["bootstrap.css","font-awesome.css","layout.scss","style.scss"]....
When I do (with or without variables):
.some-dino-class {
font-size: bigger;
}
.some-other-thingie { color: red }
It breaks.
main.css.map gives: {"version":3,"sources":["bootstrap.css","font-awesome.css","../../../stdin","../../../stdin"]....
At first I thought it has something to do with my project (maybe I overlooked something), but I downloaded the course source files with same results.
I've got this on my list to look into - definitely not just your issue :)
do we have to link ".css.map" file in the html ?
Hey Sandeep,
You don't have too, because this files needed only for debugging, i.e when you inspect an element whose styles are provided by a generated CSS file, the Elements panel displays a link to the original source file, not the generated .css file. But it's a good idea to link them, because your debugging experience will be easier.
Cheers!
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