when developing with nestjs ,
nestjs also is node server
so when changes are made , the process must be terminated and run again
in other words, bootstrap should work again

if you used express you will remember using nodemon.
you can set it up in nest as well.

reference
https://docs.nestjs.com/recipes/hot-reload

📌 hot reload

👉 package install

npm i --save-dev webpack-node-externals start-server-webpack-plugin

since it's used for development, let's install it with the -dev option

👉 webpack-hmr.config.js

https://docs.nestjs.com/recipes/hot-reload#hot-reload

create a file in the project root location
and copy and paste

const webpack = require('webpack');
const nodeExternals = require('webpack-node-externals');
const StartServerPlugin = require('start-server-webpack-plugin');

module.exports = function(options) {
  return {
    ...options,
    entry: ['webpack/hot/poll?100', options.entry],
    watch: true,
    externals: [
      nodeExternals({
        allowlist: ['webpack/hot/poll?100'],
      }),
    ],
    plugins: [
      ...options.plugins,
      new webpack.HotModuleReplacementPlugin(),
      new webpack.WatchIgnorePlugin([/\.js$/, /\.d\.ts$/]),
      new StartServerPlugin({ name: options.output.filename }),
    ],
  };
};

👉 package.json

"start": "nest start",
"start:dev": "nest build --webpack --webpackPath webpack-hmr.config.js",

👉 main.ts

const webpack = require('webpack');
const nodeExternals = require('webpack-node-externals');
const StartServerPlugin = require('start-server-webpack-plugin');

module.exports = function(options) {
  return {
    ...options,
    entry: ['webpack/hot/poll?100', options.entry],
    watch: true,
    externals: [
      nodeExternals({
        allowlist: ['webpack/hot/poll?100'],
      }),
    ],
    plugins: [
      ...options.plugins,
      new webpack.HotModuleReplacementPlugin(),
      new webpack.WatchIgnorePlugin([/\.js$/, /\.d\.ts$/]),
      new StartServerPlugin({ name: options.output.filename }),
    ],
  };
};

📌 when it doesn't work properly

https://docs.nestjs.com/recipes/hot-reload

once , i set it up as above but it doesn't work as i expected

why ??....

this is simple code

i modified a simple code to test it

so i looked at my cmd hoping it was reloaded

......... why is it cmd reloading ?