babel vs babel-core vs babel-loader vs babel-preset-2015 vs babel-preset-react vs babel-polyfill [英] babel vs babel-core vs babel-loader vs babel-preset-2015 vs babel-preset-react vs babel-polyfill

问题描述

我正在为我的React项目设置Webpack，并且在babel，babel-core，babel-loader，babel-preset-2015和babel-preset-react之间感到困惑.我知道需要Babel才能将ES7或ES6代码转换为ES5，但是在我的package.json中，我安装了除Babel之外的所有这些依赖项，它们也都作为devDependencies.

I was setting up Webpack for my React project and got confused between babel, babel-core, babel-loader, babel-preset-2015 and babel-preset-react. I know that Babel is needed to transform ES7 or ES6 code to ES5 but in my package.json I have installed all these dependencies except Babel and they also as devDependencies.

有人可以解释一下所有这些之间的区别是什么，为什么我的项目需要所有这些?难道没有任何一个依赖可以取代它们吗?如果它们是如此重要，为什么将它们包含在devDependencies中?

Can someone please explain what's the difference between all these and why all of them are needed for my project? Isn't there any single dependency to replace them all? And if they are so important, why are they included as devDependencies?

推荐答案

babel

Babel doesn't do anything,It basically acts like const babel = code => code; 
by parsing the code and then generating the same code back out again.

You will need to add some plugins for Babel to do anything like transpiling es6,JSX.

巴比伦

if you want to use babel in your real project, you need to install babel but 
there's no babel package available.

   babel split it up into two separate packages: babel-cli and babel-core

   **babel-cli** : which can be used to compile files from the command line.

   **babel-core** : if you want to use the Node API you can install babel-
      core, Same as "babel-cli" except you would use it programmatically inside your app.

   use "babel-cli" or "babel-core" to compile your files before production.

继续前进之前，

预设vs插件:

We can add features(es6,JSX) one at a time with babel plugins(es2015), 
    or 
we can use babel presets to include all the features(es6) of a particular year.

Presets make setup easier.

babel-preset-es2015

babel-preset-env supports es2015 features and replaces es2015, es2016, 
  es2017 and latest.

So use babel-preset-env, it behaves exactly the same as babel-preset-latest 
 (or babel-preset-es2015, babel-preset-es2016, and babel-preset-es2017 together).

babel预设反应

transform JSX into createElement calls like transforming react pure class to 
   function and transform react remove prop-types.

babel-polyfill

Without babel-polyfill, babel only allows you to use features like arrow 
 functions, destructuring, default arguments, and other syntax-specific 
 features introduced in ES6.

The new ES6 built-ins like Set, Map and Promise must be polyfilled

To include the polyfill you need to require it at the top of the entry point 
  to your application. 

babel-loader

you done with babel-core, babel-cli, and why need preset, plugins and now 
  you are compiling ES6 to ES5 on a file-by-file basis by babel-cli every time.

to get rid-off this, you need to bundle the task/js file. For that you need 
   Webpack.

Loaders are kind of like "tasks", They gives the ability to leverage 
 webpack's bundling capabilities for all kinds of files by converting them 
 to valid modules that webpack can process.

Webpack has great Babel support through babel-loader

devDependencies

When you deploy your app, modules in dependencies need to be installed or 
your app won't work. Modules in devDependencies don't need to be installed 
on the production server since you're not developing on that machine.

These packages are only needed for development and testing.

难道没有一个依赖项可以全部取代吗?

as you read the above states, You need some presets and loaders to transpile 
 es2015 or JSX files.

babel-> @babel

Since Babel 7 the Babel team switched to scoped packages, so you now 
have to use @babel/core instead of babel-core.

Your dependencies will need to be modified like so:

babel-cli -> @babel/cli. Ex:  babel- with @babel/.

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