I am trying to write a simple node script with some classes.
I first define a class
export default class Checkout() {
constructor () {
console.log('checkout')
}
check() {
console.log('check')
}
}
Then I am trying to use it
>node
>repl
check = new Checkout()
Uncaught ReferenceError: Checkout is not defined
require('Checkout')
Uncaught Error: Cannot find module 'Checkout'
How can I solve this? I am coming from Ruby where the console is pretty straight forward.
Code in a file isn't included in any other scope outside of that file until you require or import the file. When requiring/importing, the name the object you exported from the file doesn't automatically get used, you still have to specify it.
However, you're currently mixing require (CommonJS module format) with export default (ECMAScript Module format). There is only very limited interoperability between these formats using dynamic import(), but it's not yet available in the Node REPL (open issue here). If you need to test your Checkout class in the REPL, you'd need to just switch to using CommonJS:
module.exports = class Checkout() {
constructor () {
console.log('checkout')
}
check() {
console.log('check')
}
}
Usage:
> Checkout = require('checkout.js')
> check = new Checkout()
Related
I am currently having a TypeScript project that includes Ethers.js, which in turn includes bn.js.
The problem is
SyntaxError: The requested module './../../../bn.js/lib/bn.js' does not provide an export named 'default'
It appears to me this is because BN is in UMD format (see at https://github.com/indutny/bn.js/blob/master/lib/bn.js#L1)
(function (module, exports) {
'use strict';
// Utils
function assert (val, msg) {
if (!val) throw new Error(msg || 'Assertion failed');
}
and the correponding .ts declaration is
"use strict";
/**
* BigNumber
*
* A wrapper around the BN.js object. We use the BN.js library
* because it is used by elliptic, so it is required regardless.
*
*/
import _BN from "bn.js";
import BN = _BN.BN;
import { Bytes, Hexable, hexlify, isBytes, isHexString } from "#ethersproject/bytes";
import { Logger } from "#ethersproject/logger";
import { version } from "./_version";
const logger = new Logger(version);
It may be there's something that could be done at importing (source) or in Rollup. Difficult to tell!
Here is a screenshot of the build errors (one variation, depending on if building or running directly)
Question: Is there a way to transform this format to an ESM format in application Rollup pipeline?
I have tried using #rollup/plugin-commonjs and #rollup/plugin-node-resolve as in
resolve({ browser: true, preferBuiltins: false }), commonjs()]
(or see the project as whole at https://github.com/veikkoeeva/erc1155sample/blob/main/web/rollup.config.js, the error shows with npm run test or npm run start (in console log)).
Thus far I've had no luck cracking this, though. Hence coming here wondering if there's a dumb issue I don't see or if this is a genuinely tougher issue.
Edit: indeed, following https://rollupjs.org/guide/en/#error-name-is-not-exported-by-module and maybe named exports is the key here...
I'm trying to use cy.taks() to load certain datasets to mongo before a test is run. But I'm getting errors. I've got a module where I export 2 functions, one from dropping a collection, and the other to load an object to a collection. Here is my cypress/plugins/index.js:
module.exports = (on, config) => {
on("task", {
"defaults:db": () => {
const {dropCollection, createUser } = require("../../lib/connectDB");
dropCollection("users");
createUser(userData)
},
});
};
Here is my /lib/connecDB.js:
export function dropCollection(collection) {
return mongoose.connection.dropCollection(collection);
}
export async function createUserInDB(userData) {
await User.create(userData);
}
So when I run the test, I'm getting:
cy.task('defaults:db') failed with the following error:
Unexpected token 'export'
Tried as well importing these function outside the index.js export, but getting same result.
I'd say it is something about export/import. The functions are exported as ES6, and imported as ES5.
I've tried to import the function the ES6 like:
import { dropCollection, createUser } from '../lib/connectDB'
And then export the plugin function also as ES6, but then I get:
Error: The plugins file is missing or invalid.
Your `pluginsFile` is set to `C:\Users\someRoute\cypress\plugins\index.js`, but either the file is missing, it contains a syntax error, or threw an error when required. The `pluginsFile` must be a `.js`, `.ts`, or `.coffee` file.
I've also tried to import required modules outside the function like:
const globalDbUtils = require('../lib/connectDB')
And then use the functions as
globalDbUtils.dropCollection("collectionName")
globalDbUtils.createUser(userData)
But I'm getting last error. I've tried pretty much everything, I tried to import Mongoose models straight, mongo client etc...Also I tried to import just one function and return it (just copy/pasting official doc...) but cannot make it work. I researched for a couple of days getting nothing, I found there is a npm package that helps u doing this, but since cypress allows you to do this by using no more plugins, I'd like to do it with no more tools than cypress itself.
Anyone knows what I am doing wrong?
Thanks in advance!
You need to use require instead of import at the top of your file and when exporting at the bottom use
module.exports = { createUserInDB }
Instead of exporting as you are currently doing.
I'm fairly new to typescript but I think this issue is actually indirectly related to Node. Anyway, I'm trying to write a small node lib and I'm using Typescript.
I have a class, let's say:
//foo.ts
export class Foo {
constructor(options:Options = {}) { ... }
}
However using this class directly most times will not be desirable given the nature of my lib, so I'm also exporting a module
//module.ts
import { Foo } from './foo'
let instance
... // other methods
export function init(options: Options) {
instance = new Foo(options)
}
Everything works as I expect. The issue I have is to write unit tests for module.ts. I need to write several test cases, but once I call module.init(options) once, the instance will be created and as node cache modules, importing it again in my test file will still have the foo instance there. In vanilla javascript I used the proxyquire to generate other instances of the module, but it seems that it doesn't work so well with typescript... How would I "force" node to "re-import" a "clean" instance of my module?
How would I "force" node to "re-import" a "clean" instance of my module?
A simple factory method e.g. Change
//foo.ts
export class Foo {
constructor(options:Options = {}) { ... }
}
To:
//foo.ts
class Foo {
constructor(options:Options = {}) { ... }
}
export const create(options: Options): Foo {
return new Foo(options);
}
I'm building a project ReactJS and TypeScript and want to use a module I will share between my web application and API server.
I've used create-react-app with ts-scripts for my web app. I've made my shared module without using a starter project because it's pretty simple.
My web application references my shared module using NPM's local packages feature, the command npm install --save <path/to/shared/package>
When I do npm run start for my react app I get the error
TypeError: __WEBPACK_IMPORTED_MODULE_3_validation_shared__.ValidEmail is not a constructor
validation_shared is my unimaginative module name.
The TypeScript causing the error is
const valid_email = new ValidEmail("john.doe#example.com");
Is there anything I can change in my configs or setup to get this working? I would love to use typescript & ts-node, and have shared modules.
Edit - adding code for ValidEmail and the other function in that file.
export function validate(email_address: string): boolean {
return email_address.indexOf("#") !== -1;
}
export class ValidEmail {
public email_address: string;
constructor(email_address: string) {
if(validate(email_address)) {
this.email_address = email_address;
} else {
throw new TypeError("Invalid value for email address param, it must contains an # symbol.");
}
}
}
After more investigation it looks like whatever webpack/bundling process create-react-app uses is bundling the import definitions with the front-end code but not adding the actual class & function definitions.
I found this out by checking the generated code that is loaded into chrome and looking for actual class name "ValidEmail" which isn't present.
Edit # 2 - console.log output
I updated my App.tsx to this
import { HeaderBar, IHeaderBarProps } from "./components/headerbar";
import * as vs from "validate-shared";
class App extends React.Component {
public render() {
console.log(vs);
And the result of console.log(vs) is:
/static/media/index.9d88054a.ts
When I look at the contents of the file I see only
export * from "./ValidEmail";
export * from "./User";
This makes sense because it's the contents of my index.ts file for that module. I can't find the "meat" of the files ValidEmail or User anywhere. It looks like the actual code for those classes isn't included anywhere.
I have a TypeScript file config.ts that will be run with node:
import myDependency = require('my-dependency');
export = {
doSomething = () => {
...
}
}
In other TypeScript file, I can import this file with full type safety:
import config = require('./config');
config.doSomething();
config.doSomethingElse(); // compiler error, this method doesn't exist
Now I want to unit test this script. In order to mock out the dependencies that this script require()s I'm using proxyquire, which lets me provide the values that my script will get when it makes calls to require(). Here's what my test might look like:
import proxyquire = require('proxyquire');
const config = proxyquire('./config', {
'my-dependency': {} // this mocked object will be provided when config.ts asks for `my-dependency`
});
expect(config.doSomething()).to.do.something();
This works fine, except that my config variable is of type any because I'm using proxyquire() in place of require(). TypeScript must give the require() function special treatment to allow it to perform module resolution. Is there a way to tell the TypeScript compiler that proxyquire() should also do module resolution, similar to require()?
I could rewrite config.ts as a class or make it use an interface. Then I would be able to explicitly type the variables in my tests by importing the class/interface definition. But allowing proxyquire() to implicitly type things for me would be far be the easier solution.
There is a workaround - you can get the type of config.ts module by importing actual module and using typeof in a type cast:
import proxyquire = require('proxyquire');
import configType = require('./config');
const config = <typeof configType> proxyquire('./config', {
'my-dependency': {} // this mocked object will be provided when config.ts asks for `my-dependency`
});
config.doSomething();
// config.noSuchMethod(); // does not compile
This is not ideal because you have to import the same module in your test twice - the real one just to get at the type of it and "proxiquired" one to actually use in your tests, and you have to be careful not to mix up the two. But it's pretty simple compared to the task of implementing another variant of module resolution for typescript. Also, when configType is used in this way - for typing only - its import will not even appear in generated javacsript code.