What is the right way to use lodash-es in Angular Universal?

问题

Angular Universal server breaks when I replace my imports from lodash to lodash-es. But when I run ng serve, things are fine. I want to use lodash-es so I can cherry-pick lodash functions in my Angular SPA and shrink bundle size.

Steps I took: npm uninstalled lodash, npm installed lodash-es, and replaced my imports like this:

From: import { find as _find } from "lodash";

To: import { find as _find } from "lodash-es";

This is the server error I am getting:

/usr/src/app/node_modules/lodash-es/lodash.js:10
export { default as add } from './add.js';
^^^^^^
SyntaxError: Unexpected token export
    at createScript (vm.js:80:10)
    at Object.runInThisContext (vm.js:139:10)
    at Module._compile (module.js:599:28)
    at Object.Module._extensions..js (module.js:646:10)
    at Module.load (module.js:554:32)
    at tryModuleLoad (module.js:497:12)
    at Function.Module._load (module.js:489:3)
    at Module.require (module.js:579:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/usr/src/app/dist/server.js:246:18)

server.ts

import "zone.js/dist/zone-node";
import "reflect-metadata";
import { renderModuleFactory } from "@angular/platform-server";
import { enableProdMode } from "@angular/core";

import * as express from "express";
import * as minifyHTML from "express-minify-html";
import { join } from "path";
import { readFileSync } from "fs";

// Faster server renders w/ Prod mode (dev mode never needed)
enableProdMode();

// Express server
const app = express();

const PORT = process.env.PORT || 4000;
const DIST_FOLDER = join(process.cwd(), "dist");

// Our index.html we'll use as our template
const template = readFileSync(
  join(DIST_FOLDER, "browser", "index.html")
).toString();

// * NOTE :: leave this as require() since this file is built Dynamically from webpack
const {
  AppServerModuleNgFactory,
  LAZY_MODULE_MAP
} = require("./dist/server/main.bundle");

// Express Engine
import { ngExpressEngine } from "@nguniversal/express-engine";
// Import module map for lazy loading
import { provideModuleMap } from "@nguniversal/module-map-ngfactory-loader";

app.use(
  minifyHTML({
    override: true,
    exception_url: false,
    htmlMinifier: {
      removeComments: true,
      collapseWhitespace: true,
      collapseBooleanAttributes: true,
      removeAttributeQuotes: true,
      removeEmptyAttributes: true,
      minifyJS: true,
      minifyCSS: true
    }
  })
);

// Our Universal express-engine (found @ https://github.com/angular/universal/tree/master/modules/express-engine)
app.engine(
  "html",
  ngExpressEngine({
    bootstrap: AppServerModuleNgFactory
  })
);

app.set("view engine", "html");
app.set("views", join(DIST_FOLDER, "browser"));

/* - Example Express Rest API endpoints -
  app.get('/api/**', (req, res) => { });
*/

// Server static files from /browser
app.get(
  "*.*",
  express.static(join(DIST_FOLDER, "browser"), {
    maxAge: "1y"
  })
);

// ALl regular routes use the Universal engine
app.get("*", (req, res) => {
  res.render("index", { req });
});

// Start up the Node server
app.listen(PORT, () => {
  console.log(`Node Express server listening on http://localhost:${PORT}`);
});

This is webpack.server.config.js (might be related?):

const path = require("path");
const webpack = require("webpack");
const nodeExternals = require("webpack-node-externals");

module.exports = {
  entry: { server: "./server.ts" },
  resolve: { extensions: [".ts", ".js"] },
  target: "node",
  externals: [nodeExternals()],
  output: {
    path: path.join(__dirname, "dist"),
    filename: "[name].js"
  },
  module: {
    rules: [{ test: /\.ts$/, loader: "ts-loader" }]
  },
  plugins: [
    new webpack.DefinePlugin({
      window: undefined,
      document: undefined
    }),
    new webpack.ContextReplacementPlugin(
      /(.+)?angular(\\|\/)core(.+)?/,
      path.join(__dirname, "src"), // location of your src
      {} // a map of your routes
    ),
    new webpack.ContextReplacementPlugin(
      /(.+)?express(\\|\/)(.+)?/,
      path.join(__dirname, "src")
    )
  ]
};

回答1:

The solution is to whitelist lodash-es, as David suggested in the comments to the original question. To be specific, now webpack.server.config.js looks like this:

...
  externals: [
    nodeExternals({
      whitelist: [/^lodash-es/]
    })
  ],
...

回答2:

Angular 2+ is typescript .. so you need to install @types/lodash from npm using the command below

npm install --save @types/lodash

then you need to import that in component like:

import * as lodash from 'lodash';

you can use lodash like

lodash.find()  etc...

来源：https://stackoverflow.com/questions/47717245/what-is-the-right-way-to-use-lodash-es-in-angular-universal

标签

angular

lodash

angular-universal