webpack4与webpack3的区别webpack4与webpack3的区别webpack4与webpack3的区别webpack4.0 以后，似乎执行方式就发生了改变，不再是 webpack 一波流，而是多了一个 webpack-cli。webpack3中webpack-cli是合在webpack中。所以在命令行运行 webpack 命令的同时，会提示让你再装一个 webpack-cli。webpack4.0webpackwebpack-cliwebpack3webpack-cliwebpackwebpackwebpack-cli执行脚本到打包结束流程执行脚本到打包结束流程执行脚本到打包结束流程1、当我们安装了webpack模块后，就会在node_modules/.bin目录下生成一个webpack、webpack.cmd，webpack是linux下的命令脚本，webpack.cmd是windows下命令脚本，webpack.cmd可以在windows系统上直接运行。webpacknode_modules/.binwebpack、webpack.cmd，webpacklinuxwebpack.cmdwindowswebpack.cmdwindows每当执行npm run，就会自动新建一个 Shell，在这个 Shell 里面执行指定的脚本命令。因此，只要是 Shell（一般是 Bash）可以运行的命令，就可以写在 npm 脚本里面。npm runShell Shell
Shell Bash npm比较特别的是，npm run新建的这个 Shell，会将当前目录的node_modules/.bin子目录加入PATH变量（软连接），执行结束后，再将PATH变量恢复原样。npm runnode_modules/.binPATHPATH这意味着，当前目录的node_modules/.bin子目录里面的所有脚本，都可以直接用脚本名调用，而不必加上路径。比如，当前项目的依赖里面有 Mocha，只要直接写mocha test就可以了。node_modules/.binMochamocha test
执行一下命令
cd .\node_modules\.bin\
执行一下命令
cd .\node_modules\.bin\
2、package.json中script配置dev: webpack --mode development，当执行npm run dev相当于执行webpack --mode development
package.jsonscriptdev: webpack --mode developmentnpm run devwebpack --mode developmentwebpack.cmd执行时会判断当前目录下是否存在node执行程序，如果存在就使用当前node进程执行node_modules/webpack/bin/webpack.js，如果当前目录下不存在node进程，则使用全局（也就是本地）node执行node_modules/webpack/bin/webpack.js文件
webpack.cmdnodenodenode_modules/webpack/bin/webpack.jsnodenodenode_modules/webpack/bin/webpack.js3、node_modules/webpack/bin/webpack.js首先会判断是否安装了webpack-cli模块，如果没有安装webpack-cli模块就会引导用户去安装，如果已经安装了webpack-cli模块，就会去执行node_modules\webpack-cli\bin\cli.jsnode_modules/webpack/bin/webpack.jswebpack-cliwebpack-cliwebpack-clinode_modules\webpack-cli\bin\cli.js
CLIs = [
{

name: "webpack-cli",

package: "webpack-cli",

binName: "webpack-cli",

alias: "cli",

installed: isInstalled("webpack-cli"),

recommended: true,

url: "https://github.com/webpack/webpack-cli",

description: "The original webpack full-featured CLI."
},
{

// some coding
}
];

const installedClis = CLIs.filter(cli => cli.installed);

if (installedClis.length === 0) {
// some coding
const question = `Do you want to install 'webpack-cli' (yes/no): `;
// some coding
} else if (installedClis.length === 1) {
const path = require("path");
const pkgPath = require.resolve(`${installedClis[0].package}/package.json`);
const pkg = require(pkgPath);
console.log(path.resolve(

path.dirname(pkgPath),

pkg.bin[installedClis[0].binName]
)) // E:\项目\webpack学习\node_modules\webpack-cli\bin\cli.js
require(path.resolve(

path.dirname(pkgPath),

pkg.bin[installedClis[0].binName]
));
}
CLIs = [
{

name: "webpack-cli",

package: "webpack-cli",

binName: "webpack-cli",

alias: "cli",

installed: isInstalled("webpack-cli"),

recommended: true,

url: "https://github.com/webpack/webpack-cli",

description: "The original webpack full-featured CLI."
},
{

// some coding
}
];

const installedClis = CLIs.filter(cli => cli.installed);

if (installedClis.length === 0) {
// some coding
const question = `Do you want to install 'webpack-cli' (yes/no): `;
// some coding
} else if (installedClis.length === 1) {
const path = require("path");
const pkgPath = require.resolve(`${installedClis[0].package}/package.json`);
const pkg = require(pkgPath);
console.log(path.resolve(

path.dirname(pkgPath),

pkg.bin[installedClis[0].binName]
)) // E:\项目\webpack学习\node_modules\webpack-cli\bin\cli.js
require(path.resolve(

path.dirname(pkgPath),

pkg.bin[installedClis[0].binName]
));
}4、node_modules\webpack-cli\bin\cli.js中会require("webpack")引入webpack模块（/node_modules/lib/webpack.js）得到一个webpack函数，运行webpack函数，返回一个compiler对象，执行compiler中的run，开始编译node_modules\webpack-cli\bin\cli.jsrequire("webpack")webpack/node_modules/lib/webpack.jswebpackwebpackcompilercompilerrun
// node_modules/bin/cli.js
(function() {
// 一大堆配置
// something code ...
yargs.parse(process.argv.slice(2), (err, argv, output) => {

// something code ...

function processOptions(options) {

// 各种if else 过滤和配置

// something code...

const webpack = require("webpack");

let compiler;

try {

// 运行webpack函数，返回一个compiler对象

compiler = webpack(options);

} catch (err) {

// something code...

}

// 执行compiler中的run，开始编译。

compiler.run(compilerCallback);

}

processOptions(options);
})
// something code ...

})()
// node_modules/bin/cli.js
(function() {
// 一大堆配置
// something code ...
yargs.parse(process.argv.slice(2), (err, argv, output) => {

// something code ...

function processOptions(options) {

// 各种if else 过滤和配置

// something code...

const webpack = require("webpack");

let compiler;

try {

// 运行webpack函数，返回一个compiler对象

compiler = webpack(options);

} catch (err) {

// something code...

}

// 执行compiler中的run，开始编译。

compiler.run(compilerCallback);

}

processOptions(options);
})
// something code ...

})()
// node_modules/webpack/lib/webpack.js
const webpack = (options, callback) => {
// some coding
return compiler;
}
exports = module.exports = webpack;
// node_modules/webpack/lib/webpack.js
const webpack = (options, callback) => {
// some coding
return compiler;
}
exports = module.exports = webpack;参考：
npm 脚本的原理：https:///article/148443.htm
webpack-cli源码解析：https://www.jianshu.com/p/ec8e70d362ef参考参考https:///article/148443.htmhttps://www.jianshu.com/p/ec8e70d362ef以上就是本文的全部内容，希望对大家的学习有所帮助。