@babel/preset-env的corejs、@babel/plugin-transform-runtime的corejs之间区别

@babel/preset-env中设置corejs会污染全局环境,@babel/plugin-transform-runtime中设置仅影响局部。

babel负责转换语法,corejs (ployfill) 负责转换API。

@babel/preset-env (默认)

只转换语法,不引入 ployfill:

json 复制代码
[
   '@babel/preset-env',
   {
       corejs: 3,
       modules: false, // esm格式
   }
]
js 复制代码
// 产物格式
function _typeof(o) { "@babel/helpers - typeof"; return _typeof = "function" == typeof Symbol && "symbol" == typeof Symbol.iterator ? function (o) { return typeof o; } : function (o) { return o && "function" == typeof Symbol && o.constructor === Symbol && o !== Symbol.prototype ? "symbol" : typeof o; }, _typeof(o); }
function _extends() { return _extends = Object.assign ? Object.assign.bind() : function (n) { for (var e = 1; e < arguments.length; e++) { var t = arguments[e]; for (var r in t) ({}).hasOwnProperty.call(t, r) && (n[r] = t[r]); } return n; }, _extends.apply(null, arguments); }
function ownKeys(e, r) { var t = Object.keys(e); if (Object.getOwnPropertySymbols) { var o = Object.getOwnPropertySymbols(e); r && (o = o.filter(function (r) { return Object.getOwnPropertyDescriptor(e, r).enumerable; })), t.push.apply(t, o); } return t; }
function _objectSpread(e) { for (var r = 1; r < arguments.length; r++) { var t = null != arguments[r] ? arguments[r] : {}; r % 2 ? ownKeys(Object(t), !0).forEach(function (r) { _defineProperty(e, r, t[r]); }) : Object.getOwnPropertyDescriptors ? Object.defineProperties(e, Object.getOwnPropertyDescriptors(t)) : ownKeys(Object(t)).forEach(function (r) { Object.defineProperty(e, r, Object.getOwnPropertyDescriptor(t, r)); }); } return e; }
function _defineProperty(e, r, t) { return (r = _toPropertyKey(r)) in e ? Object.defineProperty(e, r, { value: t, enumerable: !0, configurable: !0, writable: !0 }) : e[r] = t, e; }
function _toPropertyKey(t) { var i = _toPrimitive(t, "string"); return "symbol" == _typeof(i) ? i : i + ""; }
function _toPrimitive(t, r) { if ("object" != _typeof(t) || !t) return t; var e = t[Symbol.toPrimitive]; if (void 0 !== e) { var i = e.call(t, r || "default"); if ("object" != _typeof(i)) return i; throw new TypeError("@@toPrimitive must return a primitive value."); } return ("string" === r ? String : Number)(t); }
function _slicedToArray(r, e) { return _arrayWithHoles(r) || _iterableToArrayLimit(r, e) || _unsupportedIterableToArray(r, e) || _nonIterableRest(); }
function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); }
function _unsupportedIterableToArray(r, a) { if (r) { if ("string" == typeof r) return _arrayLikeToArray(r, a); var t = {}.toString.call(r).slice(8, -1); return "Object" === t && r.constructor && (t = r.constructor.name), "Map" === t || "Set" === t ? Array.from(r) : "Arguments" === t || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(t) ? _arrayLikeToArray(r, a) : void 0; } }
function _arrayLikeToArray(r, a) { (null == a || a > r.length) && (a = r.length); for (var e = 0, n = Array(a); e < a; e++) n[e] = r[e]; return n; }
function _iterableToArrayLimit(r, l) { var t = null == r ? null : "undefined" != typeof Symbol && r[Symbol.iterator] || r["@@iterator"]; if (null != t) { var e, n, i, u, a = [], f = !0, o = !1; try { if (i = (t = t.call(r)).next, 0 === l) { if (Object(t) !== t) return; f = !1; } else for (; !(f = (e = i.call(t)).done) && (a.push(e.value), a.length !== l); f = !0); } catch (r) { o = !0, n = r; } finally { try { if (!f && null != t.return && (u = t.return(), Object(u) !== u)) return; } finally { if (o) throw n; } } return a; } }
function _arrayWithHoles(r) { if (Array.isArray(r)) return r; }
...

@babel/preset-env (useBuiltIns: usage)

转换语法,按需引入 ployfill。直接 import core-js/xxx,会影响全局

json 复制代码
[
   '@babel/preset-env',
   {
       corejs: 3,
       modules: false, // esm格式
       useBuiltIns: 'usage',
   }
]
js 复制代码
// 产物格式
function _typeof(o) { "@babel/helpers - typeof"; return _typeof = "function" == typeof Symbol && "symbol" == typeof Symbol.iterator ? function (o) { return typeof o; } : function (o) { return o && "function" == typeof Symbol && o.constructor === Symbol && o !== Symbol.prototype ? "symbol" : typeof o; }, _typeof(o); }
function _extends() { return _extends = Object.assign ? Object.assign.bind() : function (n) { for (var e = 1; e < arguments.length; e++) { var t = arguments[e]; for (var r in t) ({}).hasOwnProperty.call(t, r) && (n[r] = t[r]); } return n; }, _extends.apply(null, arguments); }
function ownKeys(e, r) { var t = Object.keys(e); if (Object.getOwnPropertySymbols) { var o = Object.getOwnPropertySymbols(e); r && (o = o.filter(function (r) { return Object.getOwnPropertyDescriptor(e, r).enumerable; })), t.push.apply(t, o); } return t; }
function _objectSpread(e) { for (var r = 1; r < arguments.length; r++) { var t = null != arguments[r] ? arguments[r] : {}; r % 2 ? ownKeys(Object(t), !0).forEach(function (r) { _defineProperty(e, r, t[r]); }) : Object.getOwnPropertyDescriptors ? Object.defineProperties(e, Object.getOwnPropertyDescriptors(t)) : ownKeys(Object(t)).forEach(function (r) { Object.defineProperty(e, r, Object.getOwnPropertyDescriptor(t, r)); }); } return e; }
function _defineProperty(e, r, t) { return (r = _toPropertyKey(r)) in e ? Object.defineProperty(e, r, { value: t, enumerable: !0, configurable: !0, writable: !0 }) : e[r] = t, e; }
function _toPropertyKey(t) { var i = _toPrimitive(t, "string"); return "symbol" == _typeof(i) ? i : i + ""; }
function _toPrimitive(t, r) { if ("object" != _typeof(t) || !t) return t; var e = t[Symbol.toPrimitive]; if (void 0 !== e) { var i = e.call(t, r || "default"); if ("object" != _typeof(i)) return i; throw new TypeError("@@toPrimitive must return a primitive value."); } return ("string" === r ? String : Number)(t); }
function _slicedToArray(r, e) { return _arrayWithHoles(r) || _iterableToArrayLimit(r, e) || _unsupportedIterableToArray(r, e) || _nonIterableRest(); }
function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); }
function _unsupportedIterableToArray(r, a) { if (r) { if ("string" == typeof r) return _arrayLikeToArray(r, a); var t = {}.toString.call(r).slice(8, -1); return "Object" === t && r.constructor && (t = r.constructor.name), "Map" === t || "Set" === t ? Array.from(r) : "Arguments" === t || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(t) ? _arrayLikeToArray(r, a) : void 0; } }
function _arrayLikeToArray(r, a) { (null == a || a > r.length) && (a = r.length); for (var e = 0, n = Array(a); e < a; e++) n[e] = r[e]; return n; }
function _iterableToArrayLimit(r, l) { var t = null == r ? null : "undefined" != typeof Symbol && r[Symbol.iterator] || r["@@iterator"]; if (null != t) { var e, n, i, u, a = [], f = !0, o = !1; try { if (i = (t = t.call(r)).next, 0 === l) { if (Object(t) !== t) return; f = !1; } else for (; !(f = (e = i.call(t)).done) && (a.push(e.value), a.length !== l); f = !0); } catch (r) { o = !0, n = r; } finally { try { if (!f && null != t.return && (u = t.return(), Object(u) !== u)) return; } finally { if (o) throw n; } } return a; } }
function _arrayWithHoles(r) { if (Array.isArray(r)) return r; }
import "core-js/modules/es.symbol.js";
import "core-js/modules/es.symbol.description.js";
import "core-js/modules/es.symbol.iterator.js";
import "core-js/modules/es.symbol.to-primitive.js";
import "core-js/modules/es.array.filter.js";
import "core-js/modules/es.array.from.js";
import "core-js/modules/es.array.iterator.js";
import "core-js/modules/es.array.map.js";
import "core-js/modules/es.array.slice.js";
import "core-js/modules/es.date.to-primitive.js";
import "core-js/modules/es.function.name.js";
import "core-js/modules/es.number.constructor.js";
import "core-js/modules/es.object.assign.js";
import "core-js/modules/es.object.get-own-property-descriptor.js";
import "core-js/modules/es.object.get-own-property-descriptors.js";
import "core-js/modules/es.object.keys.js";
import "core-js/modules/es.object.to-string.js";
import "core-js/modules/es.promise.js";
import "core-js/modules/es.regexp.exec.js";
import "core-js/modules/es.regexp.to-string.js";
import "core-js/modules/es.string.iterator.js";
import "core-js/modules/web.dom-collections.for-each.js";
import "core-js/modules/web.dom-collections.iterator.js";
...

@babel/preset-env (默认) + @babel/plugin-transform-runtime(corejs-3)

转换语法,转换API。因为 import并重命名,所以只会影响局部。

json 复制代码
presets: [
    [
        "@babel/preset-env",
        {
            corejs: 3,
            modules: false,
        }
    ]
],
plugins: [
  [
    '@babel/plugin-transform-runtime',
    {
      corejs: 3,
    },
  ],
]
js 复制代码
// js产物: 
import _extends from "@babel/runtime-corejs3/helpers/extends";
import _defineProperty from "@babel/runtime-corejs3/helpers/defineProperty";
import _slicedToArray from "@babel/runtime-corejs3/helpers/slicedToArray";
function ownKeys(e, r) { var t = _Object$keys(e); if (_Object$getOwnPropertySymbols) { var o = _Object$getOwnPropertySymbols(e); r && (o = _filterInstanceProperty(o).call(o, function (r) { return _Object$getOwnPropertyDescriptor(e, r).enumerable; })), t.push.apply(t, o); } return t; }
function _objectSpread(e) { for (var r = 1; r < arguments.length; r++) { var t = null != arguments[r] ? arguments[r] : {}; r % 2 ? ownKeys(Object(t), !0).forEach(function (r) { _defineProperty(e, r, t[r]); }) : _Object$getOwnPropertyDescriptors ? Object.defineProperties(e, _Object$getOwnPropertyDescriptors(t)) : ownKeys(Object(t)).forEach(function (r) { Object.defineProperty(e, r, _Object$getOwnPropertyDescriptor(t, r)); }); } return e; }
import _Promise from "@babel/runtime-corejs3/core-js-stable/promise";
import _mapInstanceProperty from "@babel/runtime-corejs3/core-js-stable/instance/map";
import _Object$keys from "@babel/runtime-corejs3/core-js-stable/object/keys";
import _Object$getOwnPropertySymbols from "@babel/runtime-corejs3/core-js-stable/object/get-own-property-symbols";
import _filterInstanceProperty from "@babel/runtime-corejs3/core-js-stable/instance/filter";
import _Object$getOwnPropertyDescriptor from "@babel/runtime-corejs3/core-js-stable/object/get-own-property-descriptor";
import _Object$getOwnPropertyDescriptors from "@babel/runtime-corejs3/core-js-stable/object/get-own-property-descriptors";
...

@babel/preset-env (useBuiltIns: usage) + @babel/plugin-transform-runtime(corejs-3)

转换语法,转换API。关于转换API,不会重复转译 。优先 @babel/plugin-transform-runtime 转换,之后再 @babel/preset-env 转换剩下的API

babel 中 plungins 先执行。

json 复制代码
presets: [
    [
        "@babel/preset-env",
        {
            corejs: 3,
            modules: false,
            useBuiltIns: "usage"
        }
    ]
],
plugins: [
  [
    // 用来转化语法
    '@babel/plugin-transform-runtime',
    {
      corejs: 3,
    },
  ],
]
js 复制代码
// js产物: 
import _extends from "@babel/runtime-corejs3/helpers/extends";
import _defineProperty from "@babel/runtime-corejs3/helpers/defineProperty";
import _slicedToArray from "@babel/runtime-corejs3/helpers/slicedToArray";
function ownKeys(e, r) { var t = _Object$keys(e); if (_Object$getOwnPropertySymbols) { var o = _Object$getOwnPropertySymbols(e); r && (o = _filterInstanceProperty(o).call(o, function (r) { return _Object$getOwnPropertyDescriptor(e, r).enumerable; })), t.push.apply(t, o); } return t; }
function _objectSpread(e) { for (var r = 1; r < arguments.length; r++) { var t = null != arguments[r] ? arguments[r] : {}; r % 2 ? ownKeys(Object(t), !0).forEach(function (r) { _defineProperty(e, r, t[r]); }) : _Object$getOwnPropertyDescriptors ? Object.defineProperties(e, _Object$getOwnPropertyDescriptors(t)) : ownKeys(Object(t)).forEach(function (r) { Object.defineProperty(e, r, _Object$getOwnPropertyDescriptor(t, r)); }); } return e; }
import "core-js/modules/es.object.to-string.js";
import "core-js/modules/web.dom-collections.for-each.js";
import _Promise from "@babel/runtime-corejs3/core-js-stable/promise";
import _mapInstanceProperty from "@babel/runtime-corejs3/core-js-stable/instance/map";
import _Object$keys from "@babel/runtime-corejs3/core-js-stable/object/keys";
import _Object$getOwnPropertySymbols from "@babel/runtime-corejs3/core-js-stable/object/get-own-property-symbols";
import _filterInstanceProperty from "@babel/runtime-corejs3/core-js-stable/instance/filter";
import _Object$getOwnPropertyDescriptor from "@babel/runtime-corejs3/core-js-stable/object/get-own-property-descriptor";
import _Object$getOwnPropertyDescriptors from "@babel/runtime-corejs3/core-js-stable/object/get-own-property-descriptors";
...

@babel/preset-env (useBuiltIns: usage) + @babel/plugin-transform-runtime(corejs: false)

转换语法,转换API。影响全局。

json 复制代码
presets: [
  [
    '@babel/preset-env',
    {
      corejs: 3,
      modules: false, // 打包 esm
      useBuiltIns: 'usage',
    },
  ],
  ...
],
plugins: [
  [
    '@babel/plugin-transform-runtime',
    {
      corejs: false,
    },
  ],
]
js 复制代码
// js产物
import _extends from "@babel/runtime/helpers/extends";
import _defineProperty from "@babel/runtime/helpers/defineProperty";
import _slicedToArray from "@babel/runtime/helpers/slicedToArray";
function ownKeys(e, r) { var t = Object.keys(e); if (Object.getOwnPropertySymbols) { var o = Object.getOwnPropertySymbols(e); r && (o = o.filter(function (r) { return Object.getOwnPropertyDescriptor(e, r).enumerable; })), t.push.apply(t, o); } return t; }
function _objectSpread(e) { for (var r = 1; r < arguments.length; r++) { var t = null != arguments[r] ? arguments[r] : {}; r % 2 ? ownKeys(Object(t), !0).forEach(function (r) { _defineProperty(e, r, t[r]); }) : Object.getOwnPropertyDescriptors ? Object.defineProperties(e, Object.getOwnPropertyDescriptors(t)) : ownKeys(Object(t)).forEach(function (r) { Object.defineProperty(e, r, Object.getOwnPropertyDescriptor(t, r)); }); } return e; }
import "core-js/modules/es.symbol.js";
import "core-js/modules/es.array.filter.js";
import "core-js/modules/es.array.map.js";
import "core-js/modules/es.object.to-string.js";
import "core-js/modules/es.object.get-own-property-descriptor.js";
import "core-js/modules/es.object.get-own-property-descriptors.js";
import "core-js/modules/es.object.keys.js";
import "core-js/modules/es.promise.js";
import "core-js/modules/web.dom-collections.for-each.js";
...

@babel/runtime 和 @babel/runtime-corejs2/3 的区别

  • @babel/runtime。只能处理语法关键字(例如:解构 const [x] = [1])。包括:helper、regenerato。
  • @babel/runtime-corejs2/3。等于 babel/runtime 和 babel-polyfill 一起使用。包括:helper、regenerato、corejs2/3。

corejs2 和 corejs3 的区别

  • corejs2:仅支持:全局变量(例如:Promise)静态属性(例如:Array.from)
  • corejs3:在corejs2基础上还支持:实例属性(例如:[].includes)

总结

  • 支持ployfill。两者之一必须配置 corejs2/3。
  • 影响全局 。配置 @babel/preset-env 的 corejs。
  • 影响局部 。配置 @babel/plugin-transform-runtime 的 corejs。
  • 抽离公共helper函数 。配置 @babel/plugin-transform-runtime
  • 是否可以一起使用。可以,它们不会重复转译。
  • @babel/preset-env必须配置corejs-3,否则默认corejs-2,不推荐。

公共helper函数 。指的是语法转换函数,例如: _slicedToArray,实现解构const [x] = [1]。改为从 @babel/runtime中获取,不用每个文件重复定义。

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