Find unused npm packages in package.json

Question

Is there a way to determine if you have packages in your package.json file that are no longer needed?

For instance, when trying out a package and later commenting or deleting code, but forgetting to uninstall it, I end up with a couple packages that could be deleted.

What would be an efficient way to determine if a package could safely be deleted?

Solution 1

You can use an npm module called depcheck (requires at least version 10 of Node).

1. Install the module:

    npm install depcheck -g
    or
    yarn global add depcheck
   

2. Run it and find the unused dependencies:

    depcheck
   

The good thing about this approach is that you don't have to remember the find or grep command.

To run without installing use npx:

npx depcheck 

Solution 2

There is also a package called npm-check:

npm-check

Check for outdated, incorrect, and unused dependencies.

It is quite powerful and actively developed. One of it's features it checking for unused dependencies - for this part it uses the depcheck module mentioned in the other answer.

Solution 3

Check the unused dependencies

npm install depcheck -g
depcheck

Check the outdated library

npm outdated

Solution 4

The script from gombosg is much better then npm-check.
I have modified a little bit, so devdependencies in node_modules will also be found.
example sass never used, but needed in sass-loader

#!/bin/bash
DIRNAME=${1:-.}
cd $DIRNAME
FILES=$(mktemp)
PACKAGES=$(mktemp)
# use fd
# https://github.com/sharkdp/fd
function check {
    cat package.json \
        | jq "{} + .$1 | keys" \
        | sed -n 's/.*"\(.*\)".*/\1/p' > $PACKAGES
    echo "--------------------------"
    echo "Checking $1..."
    fd '(js|ts|json)$' -t f > $FILES
    while read PACKAGE
    do
        if [ -d "node_modules/${PACKAGE}" ]; then
            fd  -t f '(js|ts|json)$' node_modules/${PACKAGE} >> $FILES
        fi
        RES=$(cat $FILES | xargs -I {} egrep -i "(import|require|loader|plugins|${PACKAGE}).*['\"](${PACKAGE}|.?\d+)[\"']" '{}' | wc -l)
        if [ $RES = 0 ]
        then
            echo -e "UNUSED\t\t $PACKAGE"
        else
            echo -e "USED ($RES)\t $PACKAGE"
        fi
    done < $PACKAGES
}
check "dependencies"
check "devDependencies"
check "peerDependencies"

Result with original script:

--------------------------
Checking dependencies...
UNUSED           jquery
--------------------------
Checking devDependencies...
UNUSED           @types/jquery
UNUSED           @types/jqueryui
USED (1)         autoprefixer
USED (1)         awesome-typescript-loader
USED (1)         cache-loader
USED (1)         css-loader
USED (1)         d3
USED (1)         mini-css-extract-plugin
USED (1)         postcss-loader
UNUSED           sass
USED (1)         sass-loader
USED (1)         terser-webpack-plugin
UNUSED           typescript
UNUSED           webpack
UNUSED           webpack-cli
USED (1)         webpack-fix-style-only-entries

and the modified:

Checking dependencies...
USED (5)         jquery
--------------------------
Checking devDependencies...
UNUSED           @types/jquery
UNUSED           @types/jqueryui
USED (1)         autoprefixer
USED (1)         awesome-typescript-loader
USED (1)         cache-loader
USED (1)         css-loader
USED (2)         d3
USED (1)         mini-css-extract-plugin
USED (1)         postcss-loader
USED (3)         sass
USED (1)         sass-loader
USED (1)         terser-webpack-plugin
USED (16)        typescript
USED (16)        webpack
USED (2)         webpack-cli
USED (2)         webpack-fix-style-only-entries

Solution 5

many of the answer here are how to find unused items.

what if.. I wanted to..

AUTOmatically -- a) find + b) Remove the unused items

---

Option 1:

1. Install this node project.

 $ npm install -g typescript tslint tslint-etc

---

2. At the root dir, add a new file tslint-imports.json

{
  "extends": [
    "tslint-etc"
  ],
  "rules": {
    "no-unused-declaration": true
  }
}

---

3. Run this at your own risk, make a backup :)

$ tslint --config tslint-imports.json --fix --project .

---

Option 2: Per @Alex

npx depcheck --json | jq '.dependencies[]' | xargs -L1 npm rm

View more solutions

Comments

[Boern]

return new Promise(function (resolve, reject) {: ReferenceError: Promise is not defined ... too bad. gonna go with npm-check

[cyberwombat]

depcheck-es6 is now merged into depcheck

[phil294]

doesnt look useful. I am using the standard angular2 cli setup and depcheck lists every package as unused which is just wrong

[Westy92]

I used this over npm-check because there's a module for gulp integration: github.com/depcheck/gulp-depcheck.

[lapint]

This package completely lagged down my Mac running High Sierra, I would not recommend using it.

[Sakshi Nagpal]

It shows some dependencies as unused which are actually getting used such as babel-cli, css-loader, sass-loader and many more which are getting used in build process.

[Doug Domeny]

For typescript, install using npm install -g depcheck typescript. However, even with this option, every dependency was listed as unused.

[Alex K]

Seems to give me the same results as depcheck. It looks like it even uses depcheck to find the unused dependencies.

[Javier Arias]

NB. depcheck doesn't take into account packages used in scripts specified in package.json

[mgarde]

npm outdatedchecks and lists current, wanted and latest package versions. No list of unused packages though.

[Kiril]

To run it just once (w/o installation) - use npx: npx depcheck

[swateek]

I had a grunt build, and this suggested to remove all grunt packages under devDependencies. Not a good idea :)

[German Attanasio]

There is an option to ignore certain packages like eslint-* or gulp-.

[sanjeev]

so now who will remove this depcheck?

[Atte Juvonen]

Doesn't work. I just ran depcheck on my Gatsby project and it listed almost all of my packages as unused even though most of them are actually used.

[German Attanasio]

@AtteJuvonen there is a way to specify which pages should be skipped like eslint or babel. What are the packages that are being listed for you?

[Atte Juvonen]

It lists a lot of packages that are actually used, including gatsby-plugin-google-analytics and typescript.

[dev27]

Didn't work for me. It listed all the packages as unused.

[Kyle Burkett]

doesnt look useful as well. I am using the standard angular setup and this also lists every package as unused which is just as wrong

[OZZIE]

it revealed some not used ones but also used ones, still helpful I guess :-) It doesn't understand webpack loaders ;-)

[OZZIE]

What about .jsx files and .ts files etc :D

[OZZIE]

Apparently using this approach we are not using react module in our React app :D

[angularrocks.com]

Running on old angular project saying No depcheck issue which is wrong as there is definitely some unused packages I can tell

[vdiaz1130]

Editors sometimes cause imports to wrap into multiple lines. Would this script catch statements where ‘import’ or ‘require’ would be on a different line than the ‘from “PACKAGE_NAME”’? In other words, does it ignore whitespace in import or require statements?

[Ayon Nahiyan]

But this is going to remove from the js files only. But ya still good.

[alex]

how about npx depcheck --json | jq '.dependencies[]' | xargs -L1 npm rm

[el-davo]

Yeah same as the rest, finding depcheck is pretty useless to be honest, lists many packages that are in use as unused.

[jjmerelo]

Seems a bit outdated now. It includes high severity vulnerabilities right now...

[Justin Dehorty]

Adding -P 32 switch to your xargs will result in a huge speedup.

[Cameron Wilby]

Best solution compared to depcheck and derivatives. Adding --max-procs|-P 32 greatly improves the speed.

[JCollier]

depcheck jacked up my dependencies pretty badly. I just blindly trusted it and removed the packages that it said were unused. My project still built, but there were unseen problems with removing the dependencies, and down the road, I had a lot of issues.

[Manwe]

Great script that nicely extended the orginal one, but it got unusable slow (even xargs -P options) on a large react app. Re-organized file searches and shared a version that should produce same output, but not necessary in the same order.

[AndyW]

tslint is deprecated as of 2019

[daveD]

depcheck didnt work for me. It listed some as unused, so I removed them. Then when I did a build, it failed to find the dependencies I just removed !!