Our team has built a small CLI used for maintenance. The package.json specifies a path for with the bin property, and everything works great; "bin": { "eddy": "./dist/src/cli/entry.js"}
Autocompletion is achived by using yargs#17.0.1. However we recently converted the project to use es6 modules, because of a migration to Sveltekit, i.e. the package.json now contains type: module. Because of this, the CLI now only works if we run with:
what works
node --experimental-specifier-resolution=node ./dist/src/cli/entry.js help
However, if we run this without the flag, we get an error "module not found":
Error [ERR_MODULE_NOT_FOUND]: Cannot find module...
So the question is
Can we somehow "always" add the experimental-specifier-resolution=node to the CLI - so we can continue to use the shorthand eddy, and utilize auto completion?
There are two probable solutions here.
Solution 1
Your entry.js file should start with a shebang like #!/usr/bin/env node. You cannot specify the flag directly here, however, if you could provide the absolute path to node directly in the shebang, you can specify the flag.
Assuming you have node installed in /usr/bin/node, you can write the shebang in entry.js like:
#!/usr/bin/node --experimental-specifier-resolution=node
(Use which node to find the absolute path)
However, this is not a very portable solution. You cannot always assume everyone has node installed in the same path. Also some may use nvm to manage versions and can have multiple version in different path. This is the reason why we use /usr/bin/env to find the required node installation in the first place. This leads to the second solution.
Solution 2
You can create a shell script that would intern call the cli entry point with the required flags. This shell script can be specified in the package.json bin section.
The shell script (entry.sh) should look like:
#!/usr/bin/env bash
/usr/bin/env node --experimental-specifier-resolution=node ./entry.js "$#"
Then, in your package.json, replace bin with:
"bin": { "eddy": "./dist/src/cli/entry.sh"}
So when you run eddy, it will run the entry.js using node with the required flag. The "$#" in the command will be replaced by any arguments that you pass to eddy.
So eddy help will translate to /usr/bin/env node --experimental-specifier-resolution=node ./entry.js help
Just add a script to your package.json:Assuming index.js is your entry point and package.json is in the same directory
{
"scripts": {
"start": "node --experimental-specifier-resolution=node index.js"
}
}
Then you can just run on your console:
npm start
I stareted my node app with node index.js and got the following message:
(node:10128) UnhandledPromiseRejectionWarning: TypeError: e.reduce is not a function
at Module.te (C:\Projects\myproject\node_modules\tronweb\dist\TronWeb.node.js:1:9236)
Now I'm interessted in whats happening. I've seen that there are mapping files TronWeb.node.js.map in the tronweb\dist directory. I started again using --inspect and opened the chrome dev tools. But in the console I see exactly the same message.
In Node v12.12.0+ sourcemaps are supported natively. Pass --enable-source-maps flag to enable them.
One caveat in Node v12.12.0 is that Error.prepareStackTrace will no longer be called when source maps are enabled. This was fixed in v12.16+.
You can use https://www.npmjs.com/package/source-map-support
$ npm install source-map-support --save-dev
Then change your run command in package.json to:
node -r source-map-support/register index.js
(Note that you should have an index.map.js next to index.js)
Can someone help me run a node.js file that has ES6 features? This is my current workflow:
Save change in file
npm run build --- builds file to my src/dist folder
cd into my dist directory
node
var file = require('./index.js')
file.someMethod()
Then when I make a change to my method, I need to repeat all the steps above again.
Does anyone know of a more efficient way to do this?
Thanks in advance!
You dont need anything if you are not using import/export. Just Install node 8.x and then run node my_file.js. Nodejs supports most of the es6 features out of the box.
If you want to use import/export then I would recommend to use typescript: https://www.typescriptlang.org/. It has compiler TS (statically typed ES6) to ES5.
Oh, and of course both babel and typescript have watcher modules (auto recompiling on file change).
It really depends on what npm run build actually does in your app. Does it run gulp/grunt? Webpack? Etc. If it's webpack there is a webpack-dev-server that you should look into.
If it's grunt or gulp then you have a custom build chain that you're working with. If all you need is to support es6 features without having to build the project then you could use something simple like babel-cli and run your file from outside the dist directory.
$ npm i -g babel-cli
$ babel-node
> var file = require('./index.js');
> file.someMethod()
By running babel-node you're running the normal node repl but with babel required. Es6 features should now be supported in the repl without needing to be compiled to es5.
You may also want to try simply updating to the latest version of node because node 8 has pretty extensive es6 support.
I imagine people commonly use Flow and Jest (and React) together, but Flow doesn't seem to know about Jest (or Jasmine) globals. When I add // #flow to my tests, I get Flow errors like this:
src/__tests__/Thing-test.js:3
3: jest.unmock('../Thing')
^^^^ identifier `jest`. Could not resolve name
src/__tests__/Thing-test.js:7
7: describe('Thing', () => {
^^^^^^^^ identifier `describe`. Could not resolve name
src/__tests__/Thing-test.js:8
8: it('does stuff', () => {
^^ identifier `it`. Could not resolve name
I could write a Flow interface for Jest/Jasmine, but that seems lengthy and like I must be missing something. Letting Flow process node_modules/jest-cli doesn't seem to help.
Although Jest is written with flow annotations they strip types for the npm version so we don't need babel to run it. Fortunately the types are already in flow-type so the solution is quite easy (just as mentioned in the comment):
npm install -g flow-typed
flow-typed install jest#22.x.x # <-- replace the version with the latest
Although I had to add this line as well to my .eslintrc.json:
{
"env": {
"jest": true
}
}
The accepted answer does not work if you use Create-React-App. Here is how you would set up jest with CRA:
1.Install flow to your project
If you use create-reat-app, here is a guide for this step.
yarn add -D flow-bin
yarn run flow init
2. Install jest flow types
npx flow-typed install jest#22 // maybe you need a different version
(You can use npx jest -v to check your jest version if you use create-react-app.)
3. Register flow-typed in config
(Update: as #Black points out in the comments, this step may not even be neccessary)
In your .flowconfig, add flow-typed to libs section.
...
[libs]
flow-typed
...
I use yarn, npm should work just the same.
If you created your project with create-react-app you have to manually add jest to your packages.json. Otherwise flow-typed won't install the needed type definitions because create-react-app doesn't add this dependency to packages.json.
yarn add --dev jest
flow-typed install
You can also run it as a one liner.
Here you go:
npm i -D flow-typed && npx flow-typed install jest#"$(npx jest -v)"
I think declare var jest: any; should do the trick (put it either on top of each test file, or somewhere in your flow lib directory).
I'm having a surprisingly hard time finding an answer to this. With plain Node.JS, you can run any js file with node path/to/file.js, with CoffeeScript it's coffee hello.coffee and ES6 has babel-node hello.js. How do I do the same with Typescript?
My project has a tsconfig.json which is used by Webpack/ts-loader to build a nice little bundle for the browser. I have a need for a build step run from the console before that, though, that would use some of the .ts files used in the project to generate a schema, but I can't seem to be able to run a single Typescript file without compiling the whole project.
How do I do the same with Typescript
You can leave tsc running in watch mode using tsc -w -p . and it will generate .js files for you in a live fashion, so you can run node foo.js like normal
TS Node
There is ts-node : https://github.com/TypeStrong/ts-node that will compile the code on the fly and run it through node 🌹
npx ts-node src/foo.ts
Run the below commands and install the required packages globally:
npm install -g ts-node typescript '#types/node'
Now run the following command to execute a typescript file:
ts-node typescript-file.ts
We have following steps:
First you need to install typescript
npm install -g typescript
Create one file helloworld.ts
function hello(person){
return "Hello, " + person;
}
let user = "Aamod Tiwari";
const result = hello(user);
console.log("Result", result)
Open command prompt and type the following command
tsc helloworld.ts
Again run the command
node helloworld.js
Result will display on console
To add to #Aamod answer above, If you want to use one command line to compile and run your code, you can use the following:
Windows:
tsc main.ts | node main.js
Linux / macOS:
tsc main.ts && node main.js
Edit: May 2022
ts-node now has an --esm flag use it.
Old Answer:
None of the other answers discuss how to run a TypeScript script that uses modules, and especially modern ES Modules.
First off, ts-node doesn't work in that scenario, as of March 2020. So we'll settle for tsc followed by node.
Second, TypeScript still can't output .mjs files. So we'll settle for .js files and "type": "module" in package.json.
Third, you want clean import lines, without specifying the .js extension (which would be confusing in .ts files):
import { Lib } from './Lib';
Well, that's non-trivial. Node requires specifying extensions on imports, unless you use the experimental-specifier-resolution=node flag. In this case, it would enable Node to look for Lib.js or Lib/index.js when you only specify ./Lib on the import line.
Fourth, there's still a snag: if you have a different main filename than index.js in your package, Node won't find it.
Transpiling makes things a lot messier than running vanilla Node.
Here's a sample repo with a modern TypeScript project structure, generating ES Module code.
I created #digitak/esrun, a thin wrapper around esbuild and that executes a TypeScript file almost instantly. esrun was made because I was disappointed with ts-node: too slow, and just didn't work most of the time.
Advantages of esrun over ts-node include:
very fast (uses esbuild),
can import ESM as well as CJS (just use the libraries of your choice and esrun will work out of the box),
there is an included watch mode, run your script with the --watch option and any change to your entry file or any of its dependencies will re-trigger the result
you can use esrun in inspect mode to use the DevTools console instead of your terminal console.
After installing, just run:
npx #digitak/esrun file.ts
Just helpful information - here is newest TypeScript / JavaScript runtime Deno.
It was created by the creator of node Ryan Dahl, based on what he would do differently if he could start fresh.
You can also try tsx.
tsx is a CLI command (alternative to node) for seamlessly running TypeScript, its build upon esbuild so its very fast.
https://github.com/esbuild-kit/tsx
Example:
npx tsx ./script.ts
As of May 2022 ts-node does support es modules
npx ts-node --esm file.ts
you will likely need to add "type": "module", to your package.json. And some of the imports might be wonky unless you turn on experimental-specifier-resolution=node
npmjs.com/package/ts-node#commonjs-vs-native-ecmascript-modules
For linux / mac you can add the ts-node-script shebang.
Install typescript / ts-node globally (see 1 below for non global install):
npm install ts-node typescript --save-dev --global
Add this as the first line in your .ts file:
#!/usr/bin/env ts-node-script
Then make the file executable:
$ chmod +x ./your-file.ts
You can then run the file directly from the command line:
$ ./your-file.ts
Notes:
1 For non global install you can install local to your project
npm install ts-node typescript --save-dev
and add the relative path to the shebang script eg:
#!/usr/bin/env ./node_modules/.bin/ts-node-script
2 Support for shebangs was officially added in ts-node v8.9.0.
Like Zeeshan Ahmad's answer, I also think ts-node is the way to go. I would also add a shebang and make it executable, so you can just run it directly.
Install typescript and ts-node globally:
npm install -g ts-node typescript
or
yarn global add ts-node typescript
Create a file hello with this content:
#!/usr/bin/env ts-node-script
import * as os from 'os'
function hello(name: string) {
return 'Hello, ' + name
}
const user = os.userInfo().username
console.log(`Result: ${hello(user)}`)
As you can see, line one has the shebang for ts-node
Run directly by just executing the file
$ ./hello
Result: Hello, root
Some notes:
This does not seem to work with ES modules, as Dan Dascalescu has pointed out.
See this issue discussing the best way to make a command line script with package linking, provided by Kaspar Etter. I have improved the shebang accordingly
Update 2020-04-06: Some changes after great input in the comments: Update shebang to use ts-node-script instead of ts-node, link to issues in ts-node.
Write yourself a simple bash wrapper may helps.
#!/bin/bash
npx tsc $1 && node ${1%%.ts}
For environments such as Webstorm where the node command cannot be changed to ts-node or npx:
npm install ts-node typescript (Install dependencies)
node --require ts-node/register src/foo.ts (Add --require ts-node/register to "Node parameters")
This answer may be premature, but deno supports running both TS and JS out of the box.
Based on your development environment, moving to Deno (and learning about it) might be too much, but hopefully this answer helps someone in the future.
Just in case anyone is insane like me and wants to just run typescript script as though it was a .js script, you can try this. I've written a hacky script that appears to execute the .ts script using node.
#!/usr/bin/env bash
NODEPATH="$HOME/.nvm/versions/node/v8.11.3/bin" # set path to your node/tsc
export TSC="$NODEPATH/tsc"
export NODE="$NODEPATH/node"
TSCFILE=$1 # only parameter is the name of the ts file you created.
function show_usage() {
echo "ts2node [ts file]"
exit 0
}
if [ "$TSCFILE" == "" ]
then
show_usage;
fi
JSFILE="$(echo $TSCFILE|cut -d"." -f 1).js"
$TSC $TSCFILE && $NODE $JSFILE
You can do this or write your own but essentially, it creates the .js file and then uses node to run it like so:
# tsrun myscript.ts
Simple. Just make sure your script only has one "." else you'll need to change your JSFILE in a different way than what I've shown.
Install ts-node node module globally.
Create node runtime configuration (for IDE) or use node in command line to run below file js file (The path is for windows, but you can do it for linux as well)
~\AppData\Roaming\npm\node_modules\ts-node\dist\bin.js
Give your ts file path as a command line argument.
Run Or Debug as you like.
Create your TypeScript file (ex. app.ts)
npm i -D typescript ts-node -> to install the dev dependencies local
npx nodemon app.ts
Using nodemon, automatically recompile app.ts every time you change the file
Here is the command
tsc index.ts --outDir .temp && node .temp/index.js && rm -rf .temp
<<<<<<<<< Compile >>>>>>>>> <<<<<<< Run >>>>>>> << Clean >>
There is also an option to run code directly from the CLI, not the *.ts file itself.
It's perfectly described in the ts-node manual.
As a first step, install ts-node globally via npm, yarn, or whatever you like.
...and now just use ts-node -e 'console.log("Hello, world!")' (you may also add the -p flag for printing code)
This little command is perfect for checking, does everything installed fine. And for finding some other error, relevant with tsconfig.json options.
We can run it using nodemon as well
nodemon ./filepath/filename.ts
This question was posted in 2015. In 2018, node recognizes both .js and .ts. So, running node file.ts will also run.