我将Webpack与React和Typescript结合使用，并且试图为浏览器本机类WebSocket创建包装器类。
该类在文件webSocketConnection.ts中，看起来像这样：
export default class WebSocketConnection extends WebSocket {
constructor(url: string, protocols?: string | string[]) {
super(url, protocols);
}
}
一个单独的文件导入并使用它
import WebSocketConnection from './webSocketConnection';
export function Connect() {
return new WebSocketConnection("<<someUrl>>");
}
它运行良好，但是在运行该网站时，我得到了NodeInvocationException: Prerendering failed because of error: ReferenceError: WebSocket is not defined。
据我了解，这是服务器端错误，原因是节点未找到WebSocket对象，即使它在客户端上也可以正常工作。仅使用new Websocket("<<someUrl>>")时，效果很好。
我的期望是，可以通过从捆绑中排除特定文件或从服务器看到该文件中解决该问题。
我的webpack.config.js是
const path = require('path');
const webpack = require('webpack');
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const CheckerPlugin = require('awesome-typescript-loader').CheckerPlugin;
const merge = require('webpack-merge');
module.exports = (env) => {
const isDevBuild = !(env && env.prod);
// Configuration in common to both client-side and server-side bundles
const sharedConfig = () => ({
stats: { modules: false },
resolve: {
extensions: ['.js', '.jsx', '.ts', '.tsx'],
alias: {
["~"]: path.resolve(__dirname, "ClientApp"),
}
},
output: {
filename: '[name].js',
publicPath: 'dist/' // Webpack dev middleware, if enabled, handles requests for this URL prefix
},
module: {
rules: [
{ test: /\.tsx?$/, include: /ClientApp/, use: 'awesome-typescript-loader?silent=true' },
{ test: /\.(png|jpg|jpeg|gif|svg)$/, use: 'url-loader?limit=25000' }
]
},
plugins: [new CheckerPlugin()]
});
// Configuration for client-side bundle suitable for running in browsers
const clientBundleOutputDir = './wwwroot/dist';
const clientBundleConfig = merge(sharedConfig(), {
entry: { 'main-client': './ClientApp/boot-client.tsx' },
module: {
rules: [
{
test: /\.css$/,
oneOf: [
{
resourceQuery: /raw/,
use: ['style-loader', 'css-loader']
},
{
use: ExtractTextPlugin.extract({ use: isDevBuild ? 'css-loader' : 'css-loader?minimize' })
}
]
},
{
test: /\.less$/,
use: ExtractTextPlugin.extract(['css-loader', 'less-loader'])
},
{
test: /\.(woff(2)?|ttf|eot|svg)(\?v=\d+\.\d+\.\d+)?$/,
use: [{
loader: 'file-loader',
options: {
name: '[name].[ext]',
outputPath: 'fonts/'
}
}]
}
]
},
output: { path: path.join(__dirname, clientBundleOutputDir) },
plugins: [
new ExtractTextPlugin('site.css'),
new webpack.DllReferencePlugin({
context: __dirname,
manifest: require('./wwwroot/dist/vendor-manifest.json')
})
].concat(isDevBuild ? [
// Plugins that apply in development builds only
new webpack.SourceMapDevToolPlugin({
filename: '[file].map', // Remove this line if you prefer inline source maps
moduleFilenameTemplate: path.relative(clientBundleOutputDir, '[resourcePath]') // Point sourcemap entries to the original file locations on disk
})
] : [
// Plugins that apply in production builds only
new webpack.optimize.UglifyJsPlugin()
])
});
// Configuration for server-side (prerendering) bundle suitable for running in Node
const serverBundleConfig = merge(sharedConfig(), {
resolve: { mainFields: ['main'] },
module: {
rules: [
{ test: /\.css$/, loader: 'ignore-loader' },
{ test: /\.less$/, loader: 'ignore-loader' }
]
},
entry: { 'main-server': './ClientApp/boot-server.tsx' },
plugins: [
new webpack.DllReferencePlugin({
context: __dirname,
manifest: require('./ClientApp/dist/vendor-manifest.json'),
sourceType: 'commonjs2',
name: './vendor'
})
],
output: {
libraryTarget: 'commonjs',
path: path.join(__dirname, './ClientApp/dist')
},
target: 'node',
devtool: 'inline-source-map'
});
return [clientBundleConfig, serverBundleConfig];
};
更新2 36pm 编译后的结果如下：
var WebSocketConnection = (function (_super) {
__extends(WebSocketConnection, _super);
function WebSocketConnection(url, protocols) {
return _super.call(this, url, protocols) || this;
}
return WebSocketConnection;
}(WebSocket));
答案 0 :(得分：1)
更新6:42 PM：经过进一步测试，原始答案确实正确构建，但运行不正确。尽管已将原型明确设置为WebSocket，但在super()期间仍将其称为WebSocketMock。
第二种方法确实起作用，只是发现您根本无法在Chrome中扩展WebSocket，因为您总是会收到错误Failed to construct 'WebSocket': Please use the 'new' operator, this DOM object constructor cannot be called as a function.
如果其他人需要扩展可以扩展 的浏览器本机类，则可以成功完成此操作：
///Inside of file webSocketConnection.ts
export interface WebSocketConnection extends WebSocket {
//Custom properties here
}
let classVar: any;
if (typeof(WebSocket) !== 'undefined') {
classVar= class WebSocketConnection extends WebSocket {
constructor(url: string, protocols?: string | string[]) {
super(url, protocols);
}
}
}
export default function(url: string, protocols?: string | string[]): WebSocketConnection {
return new classVar(url, protocols) as WebSocketConnection;
}
-
///Inside of a second file
import createWebSocket, { WebSocketConnection } from './webSocketConnection';
function DoSomething() {
//Note no "new" keyword used, because this function isn't actually a constructor
let socket: WebSocketConnection = createWebSocket("<<someUrl>>");
}
为完成起见，非TypeScript解决方案应如下所示：
///Inside of file webSocketConnection.js
let classVar;
if (typeof(WebSocket) !== 'undefined') {
classVar = class WebSocketConnection extends WebSocket {
constructor(url, protocols) {
super(url, protocols);
}
}
}
export default function(url, protocols) {
return new classVar(url, protocols);
}
-
///Inside of a second file
import createWebSocket from './webSocketConnection';
function DoSomething() {
//Note no "new" keyword used, because this function isn't actually a constructor
let socket = createWebSocket("<<someUrl>>");
}
原始答案-没用，但留在这里是因为它可能为某人提供见识
在这里，OP有效的解决方案是创建一个模拟类WebSocketMock，该类具有与WebSocket相同的属性，但未实现，并且具有WebSocketConnection扩展了WebSocketMock 。之后，如果存在，我将把WebSocketConnection的原型更新为WebSocket。该if语句在浏览器中为true，但在节点中为false。
TypeScript解决方案：
/* Mock class = WebSocketMock; new empty class that looks similar to original class
* Original class = WebSocket; browser-only class we want to extend
* New class = WebSocketConnection; class that extends original class
*/
/* Creating a blank interface, with the same name as the mock class,
* that extends the original interface we're trying to mock
* allows the mock class to have all the properties of the original class
* without having to actually implement blank versions of them
*/
interface WebSocketMock extends WebSocket {
}
/* The mock class must have the same constructor as the original class
* so that the new class can use super() with the right signature
*/
class WebSocketMock {
constructor(url: string, protocols?: string | string[]) {
}
}
// New class extends the mock class
export default class WebSocketConnection extends WebSocketMock {
constructor(url: string, protocols?: string | string[]) {
super(url, protocols);
}
//Other properties and code will be added here
}
/* Updates the prototype of the new class to use the original class
* when the original class exists. Of course, if you try to use the new
* class in an environment (read: browser) that doesn't have the original
* class, everything would break, as it's just an empty "shim"
*/
if (typeof (WebSocket) !== 'undefined')
Object.setPrototypeOf(WebSocketConnection, WebSocket);
没有打字稿，看起来可能像这样（我没有使用Webpack进行测试的没有TypeScript的环境）
class WebSocketMock {
constructor(url, protocols) {
}
}
export default class WebSocketConnection extends WebSocketMock {
constructor(url, protocols) {
super(url, protocols);
}
//Other properties and code will be added here
}
if (typeof (WebSocket) !== 'undefined')
Object.setPrototypeOf(Object.getPrototypeOf(WebSocketConnection), WebSocket);