这个问题可能已经在其他地方得到了回答,但在标记为重复之前,请帮助我解决这个问题。我指的是使用react和d3的以下codepen:https://codepen.io/swizec/pen/oYNvpQ https://codepen.io/swizec/pen/oYNvpQ
但是,我无法弄清楚这个 codepen 如何在没有任何关键字的情况下使用类中声明的变量:
class Colors extends Component {
colors = d3.schemeCategory20;
width = d3.scaleBand()
.domain(d3.range(20));
....
}
当我尝试执行此代码时,出现以下错误:
./app/components/D3IndentedTree/Chloreophath.js
Module build failed: SyntaxError: Unexpected token (13:11)
11 | // Draws an entire color scale
12 | class Colors extends Component {
> 13 | colors = d3.schemeCategory20;
| ^
14 | width = d3.scaleBand()
15 | .domain(d3.range(20));
16 |
我无法弄清楚为什么会出现此错误。我知道你不能直接在类内部声明类的变量/属性。但是为什么代码笔可以工作呢?
提前致谢!
更新:添加 webpack.config.js 文件:
var path = require('path');
var webpack = require('webpack');
var HtmlWebpackPlugin = require('html-webpack-plugin');
module.exports = {
entry: './app/index.js',
output: {
path: path.resolve(__dirname, 'dist'),
filename: 'index_bundle.js',
publicPath: '/'
},
module: {
rules: [
{ test: /\.(js)$/, use: 'babel-loader' },
{ test: /\.css$/, use: [ 'style-loader', 'css-loader'] },
{
test: /\.png$/,
loader: "url-loader?limit=100000"
},
{
test: /\.jpg$/,
loader: "file-loader"
},
{
test: /\.(woff|woff2)(\?v=\d+\.\d+\.\d+)?$/,
loader: 'url-loader? limit=10000&mimetype=application/font-woff'
},
{
test: /\.ttf(\?v=\d+\.\d+\.\d+)?$/,
loader: 'url-loader?limit=10000&mimetype=application/octet-stream'
},
{
test: /\.eot(\?v=\d+\.\d+\.\d+)?$/,
loader: 'file-loader'
},
{
test: /\.svg(\?v=\d+\.\d+\.\d+)?$/,
loader: 'url-loader?limit=10000&mimetype=image/svg+xml'
}
]
},
plugins: [new HtmlWebpackPlugin({
template: 'app/index.html'
}),
new webpack.ProvidePlugin({
"React": "react",
}),],
devServer: {
historyApiFallback: true
}
};