I am using Babel 6 with the babel-preset-es2015 preset.
When the code is transpiled, it includes in it references to Symbols, which aren't supported in Node <= v0.12.0.
throw _iteratorError;
ReferenceError: Symbol is not defined
When I google this, I keep seeing that I need the Babel polyfill.
It's huge. I don't want it. I simply want Babel to transpile everything to straight ES5.
What am I missing?
Related
I have got the latest version of npm modules and developing a nodejs application. The problem is that some npm modules support the require() and the others support the import/export statements, I cannot use them both in a file.
Having the production criteria in mind, which should I opt for either only require() or only import/export or a mix of those using the dynamic import() along with the require(). Thanks
I assume we are talking about plain JavaScript without transpiling from TypeScript or Babel.
The require() function is used to load CommonJS modules whereas the import statement is used to load ESM modules. Which of them you should or can use depends on factors such as:
does your target Node.js version support ESM? I think ESM in Nodejs support got introduced in v12, but I'm not sure how stable it is.
is your package defined as ESM or CommonJS module. That depends on the type field in your package.json, with "type": "module" for ESM and "type": "commonjs" for CommonJS: https://nodejs.org/api/packages.html#type
are your package dependencies provided as ESM or CommonJS modules. That depends on each individual package.json and their type field as well as if the package is provided as both ESM and CommonJS modules with conditional exports: https://nodejs.org/api/packages.html#conditional-exports
Unfortunately, I cannot provide a definite answer for you because that depends on your environment. ESM and import statements are going to be the future of JS, but the ESM support in the Node.js ecosystem is not on par with CommonJS yet.
With this in mind, I would opt for CommonJS modules but I would use a transpiler like TypeScript so I can still use modern features of JS.
As I know, nodejs can only understand require syntax, not the import/export statement.
So When I want to use es6 module statement in nodejs, I have to configure babel and transpile those es6 module statement into the require syntax so that nodejs can understand what to do.
https://github.com/kentcdodds/jest-cypress-react-babel-webpack/tree/tjs/jest-00
But seeing this repo, the author is using module:false with the babel configure (see .babelrc file)
As I know, module:false option prevents the es6 module statement from being transpiled.
Nodejs still cannot understand import/export statement, but how does that work without transpiling..? Any advice would be appreciated!
I am trying to convert Express.js project to binary, and I am using zeit/pkg libary. However, it gave me an error every time I try to use pkg.
Is there a way that I can force Node/Npm to use es5 instead of es6.
in your snapshot the module is being imported from ..er/node_modules/safefs/es6/lib/safefs.js
notice it is importing from es6 which has export keyword. that means its an es6 module and your node supports 'commonjs' require.
which is why this require may be failing.
you can download latest version of node where you can resolve es6 modules.
I'm using WebStorm and a newbie to it. when I use import/export statements, it gives me an error of
Unexpected token import
but if I try with require/module.exports it works fine.
N.B- I've configured language version as ES6 from Languages and Frameworks.
This is not WebStorm but Node.js that fails. While import is a part of ES6, native support for ES6 modules in Node.js is very limited and requires special setup - see https://nodejs.org/api/esm.html#esm_enabling. So, you have to compile your code with Babel first. Usually transpiling is a part of build process (using Gulp, Grunt, WebPack, etc.). Or, you can transpile your code on-the-fly by passing -r babel-register to Node.js. Of course, you need creating appropriate .babelrc and install the required modules (npm install --save-dev babel-cli babel-preset-env)
As per understanding , Node js uses CommonJS module pattern , and in CommonJS
pattern we use require() to import a node module.
In Angular 2 application development we use #angular/core , #angular/common etc
node modules.
My question is:
Why do we use "import {} from '#angular/core'"[which is ES6 module syntax]
instead of commonJS require() syntax for accessing node modules
in angular2 code files.
The reason for this, is that Angular2 is written in TypeScript.
TypeScript is a superset of ES2015, and wants to be as close to ES2015 suggested syntax as possible. That's why you use the ES2015 import {} from syntax.
However, TypeScript also comes with a built-in transpiler (tsc). Meaning you write TypeScript code, but target a specific EcmaScript version in your tsconfig.json
When targetting ES5 and looking into the transpiled code, you will
clearly see that behind the scenes TypeScript will translate import {} from to require()in the transpiled files.
When targetting ES6, of course in the transpiled code, your imports will be ES2015 imports. Be aware that when targetting ES6, you will need babel to transpile your ES6 modules to ES5 or use System.js to load your ES6 modules in the browser.
Cheers