babeljs

问题 My current rollup.config.js is commonjs(), babel({ extensions: ['.js', '.mjs', '.html', '.svelte'], runtimeHelpers: true, exclude: ['node_modules/@babel/**', 'node_modules/core-js/**' ], // <= /!\ NOT 'node_mobules/**' presets: [ ['@babel/preset-env', { // adapter to ensure IE 11 support targets: '> 0.25%, not dead, IE 11', "modules": false, "spec": true, "forceAllTransforms": true, useBuiltIns: 'usage', corejs: 3 }] ], plugins: [ '@babel/plugin-syntax-dynamic-import', [ '@babel/plugin

问题 My current rollup.config.js is commonjs(), babel({ extensions: ['.js', '.mjs', '.html', '.svelte'], runtimeHelpers: true, exclude: ['node_modules/@babel/**', 'node_modules/core-js/**' ], // <= /!\ NOT 'node_mobules/**' presets: [ ['@babel/preset-env', { // adapter to ensure IE 11 support targets: '> 0.25%, not dead, IE 11', "modules": false, "spec": true, "forceAllTransforms": true, useBuiltIns: 'usage', corejs: 3 }] ], plugins: [ '@babel/plugin-syntax-dynamic-import', [ '@babel/plugin

问题 So, my workflow up to this point was to put import "babel-polyfill"; when using features like async / await to ask babel to include the regenerator runtime in the transpilation. I see the the following problems for users requiring my module: The user is in an ES2015 environment and transpiles his code with babel-polyfill , too. Since babel-polyfill can only be required once, he will not be able to use my module at all. If I thus choose not to include babel-polyfill , babel doesn't know that

问题 So, my workflow up to this point was to put import "babel-polyfill"; when using features like async / await to ask babel to include the regenerator runtime in the transpilation. I see the the following problems for users requiring my module: The user is in an ES2015 environment and transpiles his code with babel-polyfill , too. Since babel-polyfill can only be required once, he will not be able to use my module at all. If I thus choose not to include babel-polyfill , babel doesn't know that

问题 I have a NextJS website I'm building and it's great, except that it does not work in IE 10/11 because some code is not being transpiled correctly. I'm really bad with babel and webpack, and have never had to config them myself before. I've been trying to solve by reading online for two days now, and nothing seems to work for me. The exact error I get is weakSet is not defined , and it is coming from the common.js file. Here is my .babelrc file, located in the root of my project. // .babelrc {

问题 After upgrading to babel 7.1.5 my tests fail when i'm using import * as. test.spec.js import * as Helper from "../../../../src/renderer/modules/Helper"; describe('Testing', () => { it('Should import correctly', () => { console.log(Helper.test()) // a spyOn(Helper, 'test').and.returnValue('b'); }); }); Helper.js function test() { return 'a' } export {test} ERROR 'Upgrade.spec.js (7:8)', 'a' Error: <spyOn> : test is not declared writable or has no setter Usage: spyOn(<object>, <methodName>) at

问题 After upgrading to babel 7.1.5 my tests fail when i'm using import * as. test.spec.js import * as Helper from "../../../../src/renderer/modules/Helper"; describe('Testing', () => { it('Should import correctly', () => { console.log(Helper.test()) // a spyOn(Helper, 'test').and.returnValue('b'); }); }); Helper.js function test() { return 'a' } export {test} ERROR 'Upgrade.spec.js (7:8)', 'a' Error: <spyOn> : test is not declared writable or has no setter Usage: spyOn(<object>, <methodName>) at

问题 Migrated existing webpack project to use webpack 3.5.5 and its new config. Using express server instead of webpack-dev-server. I had to setup the resolve in webpack as below. const resolve = { extensions : ['.js'], modules : [ 'node_modules', 'src', 'testApplication' ] }; When i debug this webpack application using chrome developer tools I can see the 2 versions of source files. The first one under webpack:// It is exactly matching with the source The second one under webpack-internal:// This

问题 I am trying to import a static member of a class into a file by just using standard import syntax. To give context: Destructuring works on the static method of a class: class Person { static walk() { console.log('Walking'); } } let {walk} = Person; console.log(walk); // walk function However, I thought imports behaved like destructuring assignments. If that's true, then I would expect the following to work. But, when I attempt to import the walk method, it just comes back as undefined :

问题 I've tried the babel transpiler, and it converts All let, const and var to just var, so in all, what's the difference in our code usage? I have read documents and I know what's the difference between let, const and var , but if all of them are eventually converted to var , what's the difference ? it means that there shouldn't be any meaningful differences in performance or even scope! Update (02.14.2019) : Based on the answers I understood that scope does matter and even though they are