URIError: Failed to decode param '/%PUBLIC_URL%/favicon.ico'

问题

I am new to webpack and I got the babel loader and css loader to work and project compiles successfully but when I try to access via browser I get the below error. It looks as if PUBLIC_URL is not recognized. I I believe I don't know how to configure this.

I appreciate your valuable comments.

Thanks

ℹ ｢wdm｣: Compiled successfully. URIError: Failed to decode param 
'/%PUBLIC_URL%/favicon.ico' at decodeURIComponent (<anonymous>) at 
decode_param (/home/mike/finance- 
grapher/node_modules/express/lib/router/layer.js:172:12) at Layer.match 
(/home/mike/finance- 
grapher/node_modules/express/lib/router/layer.js:123:27) at matchLayer 
(/home/mike/finance- 
grapher/node_modules/express/lib/router/index.js:574:18) at next 
(/home/mike/finance- 
grapher/node_modules/express/lib/router/index.js:220:15) at expressInit 
(/home/mike/finance- 
grapher/node_modules/express/lib/middleware/init.js:40:5) at Layer.handle 
[as handle_request] (/home/mike/finance- 
grapher/node_modules/express/lib/router/layer.js:95:5) at trim_prefix 
(/home/mike/finance- 
grapher/node_modules/express/lib/router/index.js:317:13) at 
/home/mike/finance-grapher/node_modules/express/lib/router/index.js:284:7 
at Function.process_params (/home/mike/finance- 
grapher/node_modules/express/lib/router/index.js:335:12)

Webpack.config.js

.babelrc

package.json

project folder structure

回答1:

Quick fix

What if you were to replace %PUBLIC_URL% with the actual path. I think that Babel is having issues transpiling the %. Try replacing %PUBLIC_URL%/favicon.ico with /public/favicon.ico and the issue is resolved.

Better fix

Add a new rule to your webpack.config.js.

//...
{
  test: /\.(png|svg|jpg|jpeg|gif|ico)$/,
  exclude: /node_modules/,
  use: ['file-loader?name=[name].[ext]'] // ?name=[name].[ext] is only necessary to preserve the original file name
}
//...

Then have the .ico resource copied to the dist directory by adding an import in your App.js. import '../public/favicon.ico';

In your index.html; <link rel="shortcut icon" href="favicon.ico"> to make use of your icon. No longer need to provide a path since it will be copied to the dist directory

OR:

In addition to the rule added to the webpack.config.js mentioned above, adding plugins to the webpack config may be a better way to go depending on your setup.

For me this looks like adding the npm package html-webpack-plugin to the project. Then requiring it in the webpack config; const HtmlWebpackPlugin = require('html-webpack-plugin');. Then adding plugins to the module.exports.

//...
plugins: [
  new HtmlWebpackPlugin({
    template: './public/index.html',
    filename: './index.html',
    favicon: './public/favicon.ico'
  })
]
//...

Going this route and doing the work in the webpack config means the line added to the App.js to import the favicon.ico will no longer be necessary.

EDIT: As mentioned by @Tolumide

Don't forget to configure the webpack.config appropriately per environment.

回答2:

I had the same issue and fixed it with the following:

Inside webpack.config.js in the plugins array, add HtmlWebpackPlugin and InterpolateHtmlPlugin

  new HtmlWebpackPlugin(
        Object.assign(
          {},
          {
            inject: true,
            template: paths.appHtml,
          },
          isEnvProduction
            ? {
                minify: {
                  removeComments: true,
                  collapseWhitespace: true,
                  removeRedundantAttributes: true,
                  useShortDoctype: true,
                  removeEmptyAttributes: true,
                  removeStyleLinkTypeAttributes: true,
                  keepClosingSlash: true,
                  minifyJS: true,
                  minifyCSS: true,
                  minifyURLs: true,
                },
              }
            : undefined
        )
      ),

      new InterpolateHtmlPlugin(HtmlWebpackPlugin, env.raw)

This is the documentation of InterpolateHtmlPlugin

Makes some environment variables available in index.html.
The public URL is available as %PUBLIC_URL% in index.html, e.g.:
<link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
In production, it will be an empty string unless you specify "homepage"
in `package.json`, in which case it will be the pathname of that URL.
In development, this will be an empty string.

来源：https://stackoverflow.com/questions/50824024/urierror-failed-to-decode-param-public-url-favicon-ico

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