How to use Sass inside a Polymer component

Question

I'm currently using Polymer as my front end development framework. I love SASS. Now I understand I can create a Sass file and import it like I normally would.

However, I've really gotten into the habit of using style tags within my web components.

Basically the workflow I am looking for is to be able to simply define a script tag within my Web Component maybe add type='sass; to it. Then have grunt go through and compile all of my SASS within those tags before outputting the files to my .tmp directory.

Is something like this achievable with something like Grunt or Gulp? If so what are the best modules to help me achieve this?

Answer 1

My implementation is based on a replacement of a tag inside the Polymer html file. I'm using gulp but could be changed to use simply fs.

The files structure should be as this example:

app-view
 |- app-view.html
 |- app-view.scss

app-view.html:

<dom-module id="app-view">
    <template>
        <style>
            <!-- inject{scss} -->
        </style>
    </template>
</dom-module>

app-view.scss:

:host{
    margin-top: 50px;
    justify-content: center;
    display: flex;
}
#container{
    font-size: 12px;
    h1{
        font-size: 20px;
    }
}

gulpfile.js:

var gulp = require('gulp');
var nodeSass = require('node-sass');
var path = require('path');
var fs = require('fs');
var map = require('map-stream');
var srcPath = 'src/';
var buildPath = 'build/';
var buildSrcPath = path.join(buildPath, 'target');

gulp.task('processComponents', function () {
    return gulp.src([srcPath + '/components/**/*.html'])
        .pipe(map(function (file, cb) {
            var injectString = '<!-- inject{scss} -->';
            // convert file buffer into a string
            var contents = file.contents.toString();
            if (contents.indexOf(injectString) >= 0) {
                //Getting scss
                var scssFile = file.path.replace(/\.html$/i, '.scss');
                fs.readFile(scssFile, function (err, data) {
                    if (!err && data) {
                        nodeSass.render({
                            data: data.toString(),
                            includePaths: [path.join(srcPath, 'style/')],
                            outputStyle: 'compressed'
                        }, function (err, compiledScss) {
                            if (!err && compiledScss) {
                                file.contents = new Buffer(contents.replace(injectString, compiledScss.css.toString()), 'binary');
                            }
                            return cb(null, file);
                        });
                    }
                    return cb(null, file);
                });
            } else {
                // continue
                return cb(null, file);
            }
        }))
        .pipe(gulp.dest(path.join(buildSrcPath, 'components')));
});

RESULT:

<dom-module id="app-view">
    <template>
        <style>
            :host{margin-top:50px;justify-content:center;display:flex}#container{font-size:12px}#container h1{font-size:20px}
        </style>
    </template>
</dom-module>