问题
I'm fairly new to webpack but having some problems with css-loader or file-loader.
I'm trying to load a background-image but it doesn't work quite right. The background-image isn't shown, even though the devtools show the background-image style.
If I copy the background-image style to the element.style block, everything works fine. Am I making a stupid mistake somewhere?
The body tag should have a background image. The style appears in the developer tools and there are no errors:
I can load the file 5a09e4424f2ccffb6a33915700f5cb12.jpg, but the body has no background.
If I manually copy and paste css line to element.style in the DevTools, everything works:
This happens if I bundle using webpack-dev-server or just webpack and in both Chrome and Firefox.
Other styles, such as body { background-color: red } work fine.
This is the webpack.config.js:
const path = require('path');
module.exports = {
"entry": [
'./src/index.js'
],
"output": {
"path": path.join(__dirname, 'build'),
"filename": "bundle.js"
},
devtool: "source-map",
"module": {
"loaders": [
{
"test": /\.scss$/,
"loaders": ["style", "css?sourceMap", "sass?sourceMap"]
},
{
test: /\.jpg$/,
loader: "file-loader"
}
]
},
devServer: {
contentBase: './build'
}
};
回答1:
There is currently a bug when using sourceMap with css-loader. Removing sourceMap from your css loader should fix it.
"module": {
"loaders": [
{
"test": /\.scss$/,
"loaders": ["style", "css", "sass?sourceMap"]
},
{
test: /\.jpg$/,
loader: "file-loader"
}
]
}
Issue is related to: https://github.com/webpack/css-loader/issues/296
回答2:
It seems like browsers aren't fond of relative paths to background images on the body tag. (see also CSS Background image not loading and css background-image not working properly)
Changing the code slightly seemed to do the trick:
- change the URL to an absolute URL:
background-image: url(http://localhost:8080/5a09e4424f2ccffb6a33915700f5cb12.jpg). This is hardly ideal. - add a class to body, and change the styles to reference this class:
<body class="foo">
.foo {
background-image: url('../img/test.jpg');
}
Neither of these solve the real question, but do get you unstuck.
回答3:
After struggling with this problem for a day, I finally figured out how to rewrite urls within css using postcss
webpack.config.js
const _ = require('lodash');
const ExtractTextPlugin = require("extract-text-webpack-plugin");
const argv = {
verbose: _.includes(process.argv, '-v') || _.includes(process.argv, '--verbose'),
json: _.includes(process.argv, '--json'),
production: _.includes(process.argv, '--production'),
};
module.exports = {
cache: true,
devtool: argv.production ? "source-maps" : "eval",
output: {
path: 'public/build',
filename: '[name].js',
publicPath: "/build/",
pathinfo: true // use with devtool: "eval",
},
resolve: {
modulesDirectories: ['node_modules'],
extensions: ['', '.js', '.jsx']
},
module: {
loaders: [
{
test: /\.less$/,
loader: argv.production
? ExtractTextPlugin.extract('style-loader?sourceMap=1', [
'css-loader?sourceMap=1&importLoaders=1',
'postcss-loader?sourceMap=1',
'less-loader?sourceMap=1'
]) : [
'style-loader?sourceMap=1',
'css-loader?sourceMap=1&importLoaders=1',
'postcss-loader?sourceMap=1',
'less-loader?sourceMap=1'
].join('!')
},
{
test: /\.css$/,
loader: argv.production
? ExtractTextPlugin.extract('style-loader?sourceMap=1', [
'css-loader?sourceMap=1&importLoaders=1',
'postcss-loader?sourceMap=1',
]) : [
'style-loader?sourceMap=1',
'css-loader?sourceMap=1&importLoaders=1',
'postcss-loader?sourceMap=1',
].join('!')
},
]
}
}
postcss.config.js
const argv = {
verbose: _.includes(process.argv, '-v') || _.includes(process.argv, '--verbose'),
json: _.includes(process.argv, '--json'),
production: _.includes(process.argv, '--production'),
};
module.exports = {
plugins: [
require('autoprefixer')({
browsers: [
"> 5%", // https://www.netmarketshare.com/browser-market-share.aspx?qprid=2&qpcustomd=0
"last 2 versions", // http://caniuse.com/
]
}),
require('postcss-url-mapper')(function(url) {
return argv.production ? url : url.replace(new RegExp('^/'), 'http://localhost:3000/');
})
]
};
回答4:
Webpack generates the css and <link>s them via blob: urls, which seems to cause issues with loading background images.
Development workaround
Inline the images via the file-loader in development (creates large base64 string in the css)
But allows for hot-reloading.
Production workaround
Use the ExtractTextPlugin to serve the css as normal file.
回答5:
Where is your publicPath entry in output? eg:
publicPath: 'http://localhost:5000/', // absolute path req here for images in css to work with sourcemaps on. Must be actual numeric ip to access on lan.
https://github.com/webpack/docs/wiki/configuration#outputpublicpath
回答6:
Please try using, for example:
html {
background: url(~/Public/img/bg.jpg) no-repeat center center fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}
css-loader in webpack:
{
test: /\.(css|eot|svg|ttf|woff|jpg|png)$/i,
use: ExtractTextPlugin.extract({
use: [{
loader: 'css-loader',
options: {
importLoaders: 1,
minimize: true
},
}],
}),
},
Result in bundle.css is:
html{background:url(/Public/img/bg-picking.jpg) no-repeat 50% fixed;-webkit-background-size:cover;-moz-background-size:cover;-o-background-size:cover;background-size:cover}
回答7:
You can also try using the ~ in front of your files so that the webpack falls back to the loaders require to resolve the url.
background-url: (~assets/image/myimagefile);
来源：https://stackoverflow.com/questions/37288886/webpack-background-images-not-loading