What is the difference between yarn run and npm start?

Question

Is yarn run intended to be the equivalent of npm start?

to make matters more confusing, yarn start == yarn run start — killjoy, Jul 24 '18 at 21:10

score 88 · Accepted Answer · answered Nov 15 '16 at 20:50

88

It seems yarn run start is the equivalent of npm start, which runs the script inside the start field of the script field in package.json

answered Nov 15 '16 at 20:50

daniely

7,313
5
29
46

13

`yarn start` also runs the `start` script from package.json. – Qwerty Oct 09 '18 at 11:15

score 66 · Answer 2 · edited Jul 27 '18 at 07:16

66

Few things to understand:

npm: run command is mandatory to execute user defined scripts.
yarn: run command is not mandatory to execute user defined scripts.

start command is not a user defined script name, so you may not need to specify run command to execute it.

So, all the below commands work similar!

npm start
npm run start
yarn start
yarn run start

If you have a user defined script named 'app':

npm app (Does not work!)
npm run app (Works!)
yarn app (Works!)
yarn run app (Works!)

Note: By default start runs node server.js in case not explicitly defined.

edited Jul 27 '18 at 07:16

anothernode

5,100
13
43
62

answered Jul 27 '18 at 06:52

Chandrashekhar Naik

777
6
6

The default behaviour you specified is misleading. – snehanshu.js Nov 27 '19 at 07:44
Default behaviour is also mentioned in the doc similarly https://docs.npmjs.com/cli/start.html – Chandrashekhar Naik Jan 13 '20 at 08:34
**run** is not required for `yarn run` unless the script's name is the same a yarn sub-command (e.g. "run" would need `yarn run run` which is weird and might want to be avoided). – Kevin Jun 10 '20 at 17:39

Qwerty · Answer 3 · 2021-05-17T08:47:07.880

npm start is a shortcut for npm run start

Now in terms of running scripts from package.json, all these are equivalent:

npm run start
npm start
yarn run start
yarn start

npm run myscript
npm myscript this is an error
yarn run myscript
yarn myscript

This is because run is not mandatory command for yarn, but it is for npm.

Bonus

npr start - OK
npr myscript - OK

Put this file somewhere in PATH, eg. %localappdata%\Programs\Git\cmd

npr.cmd

npm run %*

score 0 · Answer 4 · answered Nov 25 '22 at 02:49

yarn run is similar to npm run, they can be used to run the scripts in package.json.

For npm, you can leave out run when run the npm lifecycle scripts (test, start, restart, and stop), but these scripts maybe have extra effect. For example, npm start will run node server.js if the "scripts" object does not define a "start" property in package.json. see the doc npm run. You can't run script with other name leaving out run.

For yarn, you can leave out run for all the scripts in package.json, but if your script name is same as yarn built-in cli commands, the built-in cli commands will have preference over your scripts. doc yarn run.

So the best way to run scripts in package.json: never leave out run.

What is the difference between yarn run and npm start?

4 Answers4

Bonus

Linked