在esbuild中重新启动express服务器

Question

我正在尝试用esbuild创建一个简单的express服务器。这些是我的代码

import express from "express";

const app = express();
const port = 3000;

const stopServer = {
  stop: () => {},
};

export const createServer = async () => {
  app.get("/", async (req, res) => {
    res.json({
      first: "Hello",
    });
  });

  const server = app.listen(port, () => {
    console.log(`Listening on port: ${port}`);
  });

  stopServer.stop = () => {
    server.close();
  };
};

export const stop = () => {
  stopServer.stop();
  stopServer.stop = () => {};
};

esbuild.config.js

const esbuild = require("esbuild");
const path = require("path");

const restartPlugin = () => {
  return {
    name: "restart-express",
    setup(build) {
      build.onEnd(async (res) => {
        const { stop, createServer } = await import("../dist/server.js");
        stop();
        createServer();
      });
    },
  };
};

const run = async () => {
  await esbuild.build({
    entryPoints: [path.resolve(__dirname, "../src/server.ts")],
    outdir: path.resolve(__dirname, "../dist"),
    platform: "node",
    sourcemap: true,
    format: "cjs",
    watch: {
      onRebuild: async (err, res) => {
        if (err) {
          console.error(err);
        } else {
          console.log("There is some change");
        }
      },
    },
    plugins: [restartPlugin()],
  });
};

run();

插件参考：https://github.com/evanw/esbuild/issues/1258#issuecomment-834676530

如果你要运行这个应用程序，我最初会工作，但当你更改代码时，即使你刷新页面，服务器也不会更新。

我不太清楚我哪里弄错了，有什么可以帮我的吗？

Answer 1

问题是node缓存了import("..dist/server.js")，因此它永远不会返回新模块。为了解决这个问题，我们将编写一个函数

const purgeAppRequireCache = (buildPath) => {
  for (let key in require.cache) {
    if (key.startsWith(buildPath)) {
      delete require.cache[key];
    }
  }
};

这将从节点中移除高速缓存。我们也可以以这种方式使用这个函数。它解决了我的问题

const esbuild = require("esbuild");
const path = require("path");

const startPlugin = () => {
  return {
    name: "startPlugin",
    setup(build) {
      build.onEnd((res) => {
        const serverPath = path.resolve(__dirname, "../dist/server.js");
        const { stop } = require("../dist/server.js");
        stop();
        purgeAppRequireCache(serverPath);
        purgeAppRequireCache(path.resolve(__dirname, "../src"));
        const { listen } = require("../dist/server");
        listen();
      });
    },
  };
};

const run = async () => {
  await esbuild.build({
    entryPoints: [path.resolve(__dirname, "../src/server.tsx")],
    outdir: path.resolve(__dirname, "../dist"),
    platform: "node",
    sourcemap: true,
    format: "cjs",
    watch: true,
    bundle: true,
    plugins: [startPlugin()],
  });
};

run();

const purgeAppRequireCache = (buildPath) => {
  for (let key in require.cache) {
    if (key.startsWith(buildPath)) {
      delete require.cache[key];
    }
  }
};

Answer 2

如果不重新加载运行时，全局的对象和子require(xxx) maby会出现相同的错误。你可以在修改代码时使用kill and fork cluster，它和require(xxx)一样快，有示例代码：https://github.com/ymzuiku/bike/blob/master/lib/index.js

如果您需要查看kill and fork cluster示例，这里有一个相同功能包，也使用esbuild，但它使用fs.watch: esbuild

希望能对您有所帮助:)