node_modules下.bin目录下有一个webpack.cmd脚本文件，组装定位了要执行的webpack.js文件
"%~dp0\node.exe""%~dp0\..\webpack\bin\webpack.js" %*将启动文件指向了
webpack目录下的bin\webpack.js。在
webpack.js文件中，有一个runCommond方法和isInstalled判断包是否安装函数,const runCommand = (command, args) => {
const cp = require("child_process");
return new Promise((resolve, reject) => {
const executedCommand = cp.spawn(command, args, {
stdio: "inherit",
shell: true
});
executedCommand.on("error", error => {
reject(error);
});
executedCommand.on("exit", code => {
if (code === 0) {
resolve();
} else {
reject();
}
});
});
};
const isInstalled = packageName => {
try {
require.resolve(packageName);
return true;
} catch (err) {
return false;
}
};
installedClis获取已经安装的cli，这里面重要的就是CLIs数组中第一行isInstalled("webpack-cli"),指向了webpack-cli。const installedClis = CLIs.filter(cli => cli.installed);
接下来根据
filter方法找到已经安装包，处理了包路径，通过最后的require导入了wbpack-cli/bin/cli.jsconst path = require("path");
const pkgPath = require.resolve(`${installedClis[0].package}/package.json`);
// eslint-disable-next-line node/no-missing-require
const pkg = require(pkgPath);
// eslint-disable-next-line node/no-missing-require
require(path.resolve(
path.dirname(pkgPath),
pkg.bin[installedClis[0].binName]
));
在
wbpack-cli/bin/cli.js中，是一个IIFE,一般的cli文件中一般有二个操作，处理参数，将参数交给不同的逻辑（分发业务），文件中导入webpack，创建一个webpack实例。根据参数options创建一个compile实例，挂载钩子，const webpack = require("webpack");
let lastHash = null;
let compiler;
try {
compiler = webpack(options);
} catch (err) {
if (err.name === "WebpackOptionsValidationError") {
if (argv.color) console.error(`\u001b[1m\u001b[31m${err.message}\u001b[39m\u001b[22m`);
else console.error(err.message);
// eslint-disable-next-line no-process-exit
process.exit(1);
}throw err;
}【寻找webpack打包入口】在文件结尾处，就找到了webpack打包入口
run方法compiler.run((err, stats) => {
if (compiler.close) {
compiler.close(err2 => {
compilerCallback(err || err2, stats);
});
} else {
compilerCallback(err, stats);
}
});
