I'm having issues with memory leaks coming from running my test suites with Jest where memory usage keeps growing with each suite.
After searching through the net, I've found that this could be related to a garbage-collector behaviour, and multiple Github threads suggest running this command:
node --expose-gc ./node_modules/jest/bin/jest.js --coverage --runInBand --logHeapUsage
The issue is that my project uses React (with CRA not ejected) and Typescript, so whenever I run this script it throws a Syntax error because of Typescript.
I've tried installing ts-jest library but it does not work. It may be related, but running the ts-jest setup init complains about already having a configuration due to CRA.
I've been searching and I have not found anything, since all related threads are about the known memory leaks Jest has, but none explain how to execute the node command with the expose-gc in a project with React and Typescript.
Is there any way I can expose the GC to the Jest script used by CRA so I can keep using the same configuration as until now?
Otherwise, how can I execute the node --expose-gc jest parsing my files so that it does not throw an error?
I'd also need to use the --inspect-brk to see where the leak comes from, so even if the --detect-leaks works, I still need to find a way to execute my Jest config from node command.
Thank you!
After reviewing the documentation from Jest, I've seen this section which suggests to run the debug configuration in VS Code calling react-scripts. After playing a little bit with it, this is the command that got it working:
node --inspect-brk node_modules/react-scripts/scripts/test.js --no-cache --env=jsdom --runInBand
As you can see, you have to call the test.js file inside react-scripts directly, and then you can send all the arguments you want to Jest, as you'd normally do when running tests directly from the terminal of your project.
If you execute this script:
node --inspect-brk node_modules/react-scripts/bin/react-scripts.js test --no-cache --env=jsdom --runInBand
You will be able to attach to the node debugger, but you won't be able to set debugger stops in your test files, as it will attach to the main process, which is react-scripts (and not the test script itself).
Hope this might help someone in a future!
I'm using Stencil.js to create a web component library and I'm heavily relying on E2E tests. As they're rather slow it becomes more and more cumbersome to run the entire test suite (using the Stencil.js CLI) while developing new components.
However, I'm not able to run single tests in my IDE (IntelliJ IDEA) or via command line. It works perfectly fine for unit tests though.
My Jest config looks like this:
module.exports = {
"roots": [
"<rootDir>/src"
],
"preset": "#stencil/core/testing"
}
When I try to run tests in a single file (jest --config jest.config.js --testPathPattern src/components/button/button.e2e.ts$)
it fails, because
newE2EPage() is only available from E2E tests, and ran with the --e2e cmd line flag.
newE2EPage() comes with Stencil.js and I don't know what Stencil.js's CLI does in the background. Furthermore, I cloned the Stencil.js repository, just to see if it is working with their E2E tests (https://github.com/ionic-team/stencil/tree/master/test/end-to-end) but it doesn't work either.
Any idea how I can configure Jest so that it's able to run Stencil.js-E2E tests from the command line?
The --e2e flag is used for the npm script in the package.json. To start e2e tests, you can add this in your package.json:
"scripts": {
"test:e2e": "stencil test --e2e"
}
And run npm run test:e2e. For a specific file, you add it at the end like this:
npm run test:e2e src/components/button/button.e2e.ts
For more info, see the StencilJS doc: https://stenciljs.com/docs/end-to-end-testing
i have the same problem. IntelliJ and 'Run' single 'it' didnt work.
newE2EPage() is only available from E2E tests, and ran with the --e2e cmd line flag.
when i run 'npm run test' everything will work fine. the difference is that npm run stencil before and only jest dont work.
here is the stencil jest dir https://github.com/ionic-team/stencil/tree/master/src/testing/jest aswell a config.
i found in here https://stenciljs.com/docs/testing-overview a VS-CODE run jest code but no Intellij setup.
im on the run to get the path of the current file to run stencil via npm and the path the e2e file. but i cant find the correct variable for the run config.
i hope we got this solved soon.
cheers
I am not a VS Code user, but in contrast to IntelliJ there is a launch.json for VSC to run single tests: https://github.com/ionic-team/stencil-site/pull/480
I have a nodejs project written in Typescript. Therefore, i have webpack using a typescript loader that transpiles my code in Javascript and bundles it in a server.js file (in a dist folder)
When in developement conditions, my webpack runs with its watcher ON and so does nodemon.
Problem is, when i launch my script for the first time combining webpack and nodemon, since webpack is in watch mode it doesn't have an exit code saying that everything is ok, nodemon script can be started. If i run them simultaneously, nodemon will launch faster than webpack and since server.js file doesn't yet exist, it will crash at the start.
I want to launch thanks to one single command both scripts but make nodemon command wait for the bundling to be done.
First of all, when please provide some code when submitting questions.
and since server.js file doesn't yet exist
I think you should work around your setup a little bit s.t. webpack doesn't create your server.js file if you want to do this.
Basically you can chain multiple commands in a script like so webpack -d && nodemon index.js. This will launch node after webpack completes. However if you setup webpack in watch mode -w it never exists, so you can't chain another command to it. So webpack -d -w && nodemon index.js never gets to the nodemon part.
A solution to the above is to chain them using only &, which I guess you are doing, but in this way they both start at the same time. Hence, if you make your setup independent (webpack doesn't interfere with nodemon starting script) you can list them like so.
If for whatever reasons you can't do this or don't want to, your only option is with 2 separate scripts that you launch manually one after the other.
If I were you, I would just use nodemon-webpack-plugin:
Uses Nodemon to watch and restart your module's output file, but only
when webpack is in watch mode (ie, --watch).
Saves the need for installing, configuring and running Nodemon as a
seperate process.
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'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.