我的实现是基于替换Polymer html文件中的标签。我正在使用gulp，但可以更改为仅使用fs。
文件结构应该像这个例子:
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$/i, '.scss');
fs.readFile(scssFile, function (err, data) {
if (!err && data) {
nodeSass.render({
data: data.toString(),
includePaths: [path.join(srcPath, 'style/')],
outputStyle: 'compressed'
}, function (err, compiledScss) {
if (!err && compiledScss) {
file.contents = new Buffer(contents.replace(injectString, compiledScss.css.toString()), 'binary');
}
return cb(null, file);
});
}
return cb(null, file);
});
} else {
// continue
return cb(null, file);
}
}))
.pipe(gulp.dest(path.join(buildSrcPath, 'components')));
});
结果：
<dom-module id="app-view">
<template>
<style>
:host{margin-top:50px;justify-content:center;display:flex}#container{font-size:12px}#container h1{font-size:20px}
</style>
</template>
</dom-module>
var gulp = require('gulp');
var nodeSass = require('node-sass');
var path = require('path');
var fs = require('fs');
var map = require('map-stream');
var basePath = "app/";
var excludeDir = basePath+"bower_components/";
var ext = "**/*.html";
/**
* We need to specify to nodeSass the include paths for Sass' @import
* command. These are all the paths that it will look for it.
*
* Failing to specify this, will NOT Compile your scss and inject it to
* your .html file.
*
*/
var includePaths = ['app/elements/**/'];
gulp.task('watchSass', function(){
gulp.watch(['app/**/*.scss', '!app/bower_components/**/*.scss'], ["injectSass"]);
});
//This is currently not used. But you can enable by uncommenting
// " //return gulp.src([basePath+ext,...excludeDirs])" above the return.
var excludeDirs = [`!${basePath}/bower_components/${ext}`,`!${basePath}/images/${ext}`]
/**
*
* Enable for advanced use:
*
*
*/
gulp.task('injectSass', function () {
/* Original creator: David Vega. I just modified
* it to take advantage of the Polymer 1.1's shared styles.
*
* This will look all the files that are inside:
* app/elements folder. You can change this to match
* your structure. Note, this gulp script uses convention
* over configuration. This means that if you have a file called
* my-element-styles.html you should have a file called
* my-element-styles.scss
*
* Note #2:
* We use "!" (Exclamation Mark) to exclude gulp from searching these paths.
* What I'm doing here, is that Polymer Starter Kit has inside its app folder
* all the bower dependencies (bower_components). If we don't specify it to
* exclude this path, this will look inside bower_components and will take a long time
* (around 7.4 seconds in my machine) to replace all the files.
*/
//Uncomment if you want to specify multiple exclude directories. Uses ES6 spread operator.
//return gulp.src([basePath+ext,...excludeDirs])
return gulp.src([basePath+ext, '!'+excludeDir+ext])
.pipe(map(function (file, cb) {
//This will match anything between the Start Style and End Style HTML comments.
var startStyle = "<!-- Start Style -->";
var endStyle = "<!-- End Style -->";
//Creates the regEx this ways so I can pass the variables.
var regEx = new RegExp(startStyle+"[\\s\\S]*"+endStyle, "g");
// Converts file buffer into a string
var contents = file.contents.toString();
//Checks if the RegEx exists in the file. If not,
//don't do anything and return.
//Rewrote the if for reduced nesting.
if (!regEx.test(contents)) {
//Return empty. if we return cb(null, file). It will add
//the file that we do not want to the pipeline!!
return cb();
}
/**
* Getting scss
* This will get the .html file that matches the current name
* This means that if you have my-app.component.html
* this will match my-app.component.scss. Replace with .sass if you
* have .sass files instead.
*/
var scssFile = file.path.replace(/\.html$/i, '.scss');
fs.readFile(scssFile, function (err, data) {
//Rewrote the if for reduced nesting.
//If error or there is no Sass, return null.
if (err || !data) {
return cb();
}
nodeSass.render({
data: data.toString(),
includePaths: [path.join('app', 'style/'), ...includePaths],
outputStyle: 'compressed'
}, function (err, compiledScss) {
//Rewrote the if for reduced nesting.
//If error or there is no Sass, return null.
if (err || !compiledScss)
return cb();
/**
* What we are doing here is simple:
* We are re-creating the start and end placeholders
* that we had and inject them back to the .html file
*
* This will allow us to re-inject any changes that we
* do to our .scss or files.
*
*/
var injectSassContent = startStyle +
"<style>" +
compiledScss.css.toString() +
"</style>" +
endStyle;
//This is going to replace everything that was between the <!-- Start Style --> and
// "<!-- End Style -->"
file.contents = new Buffer(contents.replace(regEx, injectSassContent), 'binary');
//This return is necessary, or the modified map will not be modified!
return cb(null,file);
});
});
}))
.pipe(gulp.dest(basePath));
}); //Ends
1) 设置你的元素：
假设你有一个名为“hero-tournament”的元素：
<dom-module id="hero-tournament">
<template>
<style>
</style>
</template>
<script>
(function() {
'use strict';
Polymer({
is: 'hero-tournament',
});
})();
</script>
</dom-module>
您想将您的.scss文件注入其中。
在此之外，创建两个新文件：
hero-tournament-style.html
hero-tournament-style.scss
<!-- hero-tournament-style.html -->
<dom-module id="hero-tournament-style">
<template>
<!-- Start Style -->
<style>
</style>
<!-- End Style -->
</template>
</dom-module>
<!-- Start Style --> <!-- End Style -->
评论？
这些是非常重要的，因为所有的CSS都将放在这些标签内。它们对大小写敏感，但不对位置敏感。一定要在您的模板标签内部和样式标签外部包含它们。
然后，在您的hero-tournament-style.scss文件中，包含您的Sass CSS： （示例）
.blank{
display: none;
}
2) 运行 Gulp：
gulp watchSass
<!-- -hero-tournament-style.html -->
<dom-module id="-hero-tournament-style">
<template>
<!-- Start Style -->
<style>.blank{display:none}
</style><!-- End Style -->
</template>
</dom-module>
<!-- import the module -->
<link rel="import" href="../path-to-my-element/.html">
<dom-module id="hero-tournament">
<template>
<!-- include the style module by name -->
<style include="hero-tournament-styles"></style>
</template>
<script>
(function() {
'use strict';
Polymer({
is: 'hero-tournament',
});
})();
</script>
</dom-module>
一些最后的说明：
使用SASS导入 使用Sass导入很容易，只需要注意以下几点：
在gulpfile中有一个名为“includePaths”的变量。这是一个数组，nodeSass将查找所有导入文件。如果未指定导入文件的任何位置，将阻止您的文件注入和编译。默认情况下，在脚本中有一个'app/style'目录，它将查找文件。
文件夹结构 文件夹结构很重要，可以根据您的喜好进行调整。 假设您的元素位于与gulpfile相同层次的“app”文件夹内：
-gulpfile.js
/app
/element
/hero-tournament
-hero-tournament.html
-hero-tournament-styles.html
-hero-tournament-styles.scss
/maybe-other-folder
gulp watchSass
gulp injectSass
<dom-module id="your-module-name">
<template>
<style><!-- you can also add additional styling in here --></style>
<link rel="stylesheet" href="link_to_stylesheet.css">
<!-- your template in here -->
</template>
<script>
//your element class + registration here
</script>
</dom-module>
在样式表中，您可以像在style标签中一样为内容设置样式。这些样式仅影响元素及其内容。 如果您想使用SASS、Stylus、LESS或类似的东西，您只需要在Express中使用一个中间件（如何：Stack Overflow），该中间件会在每个请求中将SASS代码呈现为CSS。我更喜欢这种解决方案而不是GULP/GRUNT任务，因为我认为它更容易，因为由于中间件的缘故，只要需要编译，它就会自动编译。
希望这能帮到您