importing class in Node js with typescript

Question

I would import class in nodejs and use it in app.ts

var nano = require("nano");
import { EnvConfig } from './envConfig.service';
let config = new EnvConfig();
const dbCredentials: any = config.appEnv.getServiceCreds('dataservices');
export const nanodb = nano({
  url: dbCredentials.url,
});
export const nanodbCockpitLight = nanodb.use('data');
console.log(dbCredentials);

When I try to compile I get this error.

import { EnvConfig } from './envConfig.service';
       ^
SyntaxError: Unexpected token {

I have created the tsconfig file :

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": false,
    "noImplicitAny": false,
    "removeComments": true,
    "noLib": false,
    "allowSyntheticDefaultImports": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "target": "es6",
    "sourceMap": true,
    "allowJs": true,
    "outDir": "./dist",
    //"baseUrl": "src" // Attention !! nécessite l'utilisation d'un loader de module node pour fonctionner sur node
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "**/*.spec.ts"]
}

I get this warning

No inputs were found in config file 'c:/Users/EHHD05911.COMMUN/Documents/cockpitLight/DB mananger/tsconfig.json'. Specified 'include' paths were '["src//"]' and 'exclude' paths were '["node_modules","/.spec.ts"]'

Sunil Patel · Accepted Answer · 2018-10-29 16:55:42Z

2

You cannot run node app.ts file directly that won't work You need transpiler like babel js or typescript compiler tsc so first transpile to js file and then run node app.js

answered Oct 29, 2018 at 16:55

Sunil Patel

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1 Comment

nwayve Over a year ago

Well, yes and no. Create app.ts with console.log('hello world'); and run node app.ts. "hello world" is printed out. This is because typescript is a superset of javascript and if nothing needs to be transpiled, it works. You can take any .js file, rename it to .ts and so long as it was valid js, it's valid ts. However, once you add typescript syntax (const foo: string = 'bar';) then it breaks.

Gabriel Balsa Cantú · Accepted Answer · 2018-10-29 16:02:43Z

1

You're using .js extension, you need .ts extension, e.g.: app.ts instead of app.js.

Make sure you have typescript either in npm global or in dev dependencies.

answered Oct 29, 2018 at 16:02

Gabriel Balsa Cantú

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infodev Over a year ago

I have added typescript in dev dependencies but still have same problem

nwayve · Accepted Answer · 2018-10-29 23:57:05Z

1

I suspect whatever you're importing has typescript syntax (strong typing and such), and so running node directly won't work. You need to run tsc first, which will transpile everything to javascript in a dist folder, and then run node dist/app.js.

This is a bit cumbersome though, which is why there is ts-node. It's exactly what it sounds like, a node REPL for typescript. You should be able to run ts-node src/app.ts.

answered Oct 29, 2018 at 23:57

nwayve

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Comments

Loic Coenen · Accepted Answer · 2018-10-29 15:57:08Z

-1

import { something } is a typescript syntax, it won't work in a .js file. That is a separate language. Try using require instead.

answered Oct 29, 2018 at 15:57

Loic Coenen

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4 Comments

infodev Over a year ago

I'm hard coding file name to app.ts,

Loic Coenen Over a year ago

How are you trying to run it exactly? Please post your command line.

infodev Over a year ago

simply node app.ts

nwayve Over a year ago

This has less to do with typescript/javascript and more with module loading in node. import works for both typescript and es2015+ but you need a transpiler (typescript/babel) in order to change the import statements to require. No need to do this manually.

Amit Bhoyar · Accepted Answer · 2018-10-29 16:11:25Z

-1

Use babel js which is a toolchain that is mainly used to convert ECMAScript 2015+ code into a backwards compatible version of JavaScript in current and older browsers or environments.

package.json

"dependencies": {
"@babel/polyfill": "^7.0.0",
}

"babel": {
"presets": [
  "@babel/preset-env"
]

},

"scripts": {
    "start": "server.js --exec babel-node",
}

https://babeljs.io/docs

This will enable/resolve your import statements.

answered Oct 29, 2018 at 16:11

Amit Bhoyar

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1 Comment

nwayve Over a year ago

babel js is a good option but the question is specifically asking about node and typescript, which for this scenario, the typescript compiler (tsc) is the answer.

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