Importing node modules to web worker in React/Webpack app

问题

I have a React app bundled with Webpack. I would like to use a web worker for one of my components, which exports data to Pdf. The generation of the pdf can take a while and lock the browser, so I want to do this work in a web worker to do it in a separate thread. The problem I am having is importing the JsPDF library into my web worker script so i can use it.

This is my worker script:

import * as JsPDF from "jspdf";

export default () => {
    self.addEventListener("message", event => {
        const canvases = event.data;

        const pdf = new JsPDF({
            orientation: "l",
            unit: "in",
        });
        // tslint:disable-next-line:prefer-for-of
        for (let i = 0; i < canvases.length; i++) {
            if (i > 0) pdf.addPage();
            pdf.addImage(canvases[i].toDataURL("image/png"), "PNG", 0.25, 0, 11, 8);
        }
        pdf.save("report.pdf");
        self.postMessage("done", "");
    });
};

This gives me this error at runtime:

Uncaught ReferenceError: jspdf__WEBPACK_IMPORTED_MODULE_0__ is not defined
    at blob:http://localhost:11449/ea75c456-15ee-45e9-b82b-902c518dc635:4

I did also try using the importScript() function, like so:

export default () => {
    importScripts("jspdf");
    self.addEventListener("message", event => {
        const canvases = event.data;

        const pdf = new JsPDF({
            orientation: "l",
            unit: "in",
        });
        // tslint:disable-next-line:prefer-for-of
        for (let i = 0; i < canvases.length; i++) {
            if (i > 0) pdf.addPage();
            pdf.addImage(canvases[i].toDataURL("image/png"), "PNG", 0.25, 0, 11, 8);
        }
        pdf.save("report.pdf");
        self.postMessage("done", "");
    });
};

and I get this error:

Uncaught DOMException: Failed to execute 'importScripts' on 'WorkerGlobalScope': The URL 'jspdf' is invalid.

or I try:

importScripts("../../../../node_modules/jspdf/dist/jspdf.min.js");

and I get the same invalid URL error. I also tried using require outside of the export:

const JsPDF = require("jspdf");

but i still get an error that JsPDF is not defined. What else can I try?

I should mention that the web worker is instantiated using a custom class, as in https://medium.com/prolanceer/optimizing-react-app-performance-using-web-workers-79266afd4a7, for getting the correct URL with webpack:

export default class WebWorker {
    constructor(worker: any) {
        const code = worker.toString();
        const blob = new Blob([`(${code})()`]);
        return new Worker(URL.createObjectURL(blob));
    }
}

回答1:

I ended up using worker-loader for webpack. This allows me to import modules in worker scripts like in any other script.

来源：https://stackoverflow.com/questions/55029418/importing-node-modules-to-web-worker-in-react-webpack-app

标签

reactjs

Webpack

import

web-worker