Only 39% of the functions in node_modules are unique in the default Angular project created by ng new my-app.

I think the developers of open source solve problems in the same ways, because they study the same algorithms. Well, why be honest, they copy the popular solutions from StackOverflow also.

How to compare functions in Javascript?

If you want to compare functions in Javascript, then just convert them to string form:

const a = () => 'hi';
a.toString(); // "() => 'hi'"

If variable names are different

It is necessary to bring them to the same form using the UglifyJs library. UglifyJs will minimizes functions, remove unnecessary strings, and make simple calculations.

How do you extract functions from a Javascript file?

For this I used the Esprima library. We parse the file and walk an AST tree. I think that it would be possible only with Uglifyjs, but something was wrong and I was too lazy to figure it out.

Action plan

Iterate through all the * .js files in the directory
Parse each file and extract functions of types ArrowFunctionExpression,FunctionExpression and FunctionDeclaration
Compress each of the functions using UglifyJs and write it to a file whose name is the hash of the function
Put the id, path and hash to the separate file info.csv
Load the file info.csv intoSQLite and make all kinds of queries, because this database is not a toy!

Implementation details

I named all arrow functions and functional expressions z;
I renamed the usual functions to MORK, but kept the original names separately, because the function may be the same, but have a different name;
Perhaps with these renames I lost some of the statistics related to recursive functions, well, okay!

Extracting functions from a file

Listing of the file from which we will extract functions:

(function () {
    const arbuz = (test) => {
        function apple(t) {
            function test () {
                return 'ttt';
            }
            return t + 3;
        }
        const aa = 1;
        const b1 = () => 2;
        // comment
        return aa + b1() + apple(test);
    }
    return arbuz;
 })();

Note that some of the expressions are calculated, that's comfortable for function comparing. The list of the extracted functions:

"const z=function(){return n=>{return 3+(n+3)}};";
"const z=n=>{return 3+(n+3)};";
"function MORK(n){return n+3}";
"function MORK(){return"ttt"}";
"const z=()=>2;";

Full script can be found here

First research object: `node_modules` of the default Angular 11 project

So, we have to create a project using @angular/cli: ng new my-app and run our script to parse node_modules. It can take a lot of time.

View package.json

{
  "name": "my-app",
  "version": "0.0.0",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build --prod",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "~11.2.10",
    "@angular/common": "~11.2.10",
    "@angular/compiler": "~11.2.10",
    "@angular/core": "~11.2.10",
    "@angular/forms": "~11.2.10",
    "@angular/platform-browser": "~11.2.10",
    "@angular/platform-browser-dynamic": "~11.2.10",
    "@angular/router": "~11.2.10",
    "rxjs": "~6.6.0",
    "tslib": "^2.0.0",
    "zone.js": "~0.11.3"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.1102.9",
    "@angular/cli": "~11.2.9",
    "@angular/compiler-cli": "~11.2.10",
    "@types/jasmine": "~3.6.0",
    "@types/node": "^12.11.1",
    "codelyzer": "^6.0.0",
    "jasmine-core": "~3.6.0",
    "jasmine-spec-reporter": "~5.0.0",
    "karma": "~6.1.0",
    "karma-chrome-launcher": "~3.1.0",
    "karma-coverage": "~2.0.3",
    "karma-jasmine": "~4.0.0",
    "karma-jasmine-html-reporter": "^1.5.0",
    "protractor": "~7.0.0",
    "ts-node": "~8.3.0",
    "tslint": "~6.1.0",
    "typescript": "~4.1.5"
  }
}

The package-lock.json here

Results

The node_modules folder contains 26982 * .js files:

$ find . -name '*.js' | wc -l
26982

Number of functions found: 338230

sqlite> select count(*) from info;
338230

Including unique: 130886

sqlite> Select count(*) from (SELECT hash, count(id) as c FROM info group By hash);
130886

Whence it follows that 130886/338230 * 100% = 39% of the functions are really unique, and the rest are duplicates of existing ones.

You can download the csv file for self-checking here.

Top 20 most popular functions in `node_modules` for an Angular project

Function with the largest number of duplicates.

SELECT hash, count(id) as c FROM info group By hash order by c desc LIMIT 20;

#	id	number of duplicates
1	285d00ca29fcc46aa113c7aefc63827d	2730
2	cf6a0564f1128496d1e4706f302787d6	1871
3	12f746f2689073d5c949998e0216f68a	1174
4	7d1e7aad635be0f7382696c4f846beae	772
5	c2da306af9b041ba213e3b189699d45c	699
6	c41eb44114860f3aa1e9fa79c779e02f	697
7	5911b29c89fa44f28ce030aa5e433327	691
8	05c2b9b254be7e4b8460274c1353b5ad	653
9	fcaede1b9e574664c893e75ee7dc1d8b	652
10	e743dd760a03449be792c00e65154a48	635
11	777c390d3cc4663f8ebe4933e5c33e9d	441
12	27628ad740cff22386b0ff029e844e85	385
13	f6822db5c8812f4b09ab142afe908cda	375
14	d98a03a472615305b012eceb3e9947d5	330
15	4728096fca2b3575800dafbdebf4276a	324
16	7b769d3e4ba438fc53b42ad8bece86ba	289
17	7d6f69751712ef9fa94238b38120adc6	282
18	b7081aad7510b0993fcb57bfb95c5c2c	255
19	d665499155e104f749bf3a67caed576a	250
20	99fa7dfce87269a564fc848a7f7515b9	250

285d00ca29fcc46aa113c7aefc63827d, 2730 identical
```
const z=function(){};
```
cf6a0564f1128496d1e4706f302787d6, 1871 identical, function names usually: __export
```
function MORK(r){for(var o in r)exports.hasOwnProperty(o)||(exports[o]=r[o])}
```
12f746f2689073d5c949998e0216f68a, 1174 identical, function names_interopRequireDefault и __importDefault
```
function MORK(e){return e&&e.__esModule?e:{default:e}}
```
7d1e7aad635be0f7382696c4f846beae, 772 identical
```
function MORK(){}
```
c2da306af9b041ba213e3b189699d45c, 699 identical
```
const z=function(o,_){o.__proto__=_};
```
c41eb44114860f3aa1e9fa79c779e02f, 697 identical, functions name: __
```
function MORK(){this.constructor=d}
```

5911b29c89fa44f28ce030aa5e433327, 691 identical

const z=function(n,o){for(var r in o)o.hasOwnProperty(r)&&(n[r]=o[r])};

05c2b9b254be7e4b8460274c1353b5ad, 653 identical

const z=function(t,n){return extendStatics=Object.setPrototypeOf||{__proto__:[]}instanceof Array&&function(t,n){t.__proto__=n}||function(t,n){for(var o in n)n.hasOwnProperty(o)&&(t[o]=n[o])},extendStatics(t,n)};

fcaede1b9e574664c893e75ee7dc1d8b, 652 identical

const z=function(t,o){function e(){this.constructor=t}extendStatics(t,o),t.prototype=null===o?Object.create(o):(e.prototype=o.prototype,new e)};

e743dd760a03449be792c00e65154a48, 635 identical

function(){var r=function(t,o){return(r=Object.setPrototypeOf||{__proto__:[]}instanceof Array&&function(t,o){t.__proto__=o}||function(t,o){for(var n in o)o.hasOwnProperty(n)&&(t[n]=o[n])})(t,o)};return function(t,o){function n(){this.constructor=t}r(t,o),t.prototype=null===o?Object.create(o):(n.prototype=o.prototype,new n)}};

777c390d3cc4663f8ebe4933e5c33e9d, 441 identical, function names usually: Rule, AsapScheduler, ComplexOuterSubscriber и другие
```
function MORK(){return null!==_super&&_super.apply(this,arguments)||this}
```
27628ad740cff22386b0ff029e844e85, 385 identical, function names usually: identity, forwardResolution и тд
```
function MORK(n){return n}
```
f6822db5c8812f4b09ab142afe908cda, 375 identical
```
const z=function(n){};
```
d98a03a472615305b012eceb3e9947d5, 330 identical
```
const z=function(n,c){};
```
4728096fca2b3575800dafbdebf4276a, 324 identical
```
const z=function(n){return n};
```

7b769d3e4ba438fc53b42ad8bece86ba, 289 identical, function names:plural

function MORK(t){var r=Math.floor(Math.abs(t)),t=t.toString().replace(/^[^.]*\.?/,"").length;return 1===r&&0===t?1:5}

7d6f69751712ef9fa94238b38120adc6, 255 identical
```
const z=function(){return this};
```
b7081aad7510b0993fcb57bfb95c5c2c, 250 identical
```
const z=function(){return!1};
```
d665499155e104f749bf3a67caed576a, 250 identical
```
const z=function(n){return null==n};
```

99fa7dfce87269a564fc848a7f7515b9, 255 identical

const z=function(a,c){this._array.forEach(a,c)};

Files with the largest number of functions

SELECT count(id) as c, path FROM info group By path order by c desc LIMIT 20;

quantity	file
13638	`typescript/lib/tsserver.js`
13617	`typescript/lib/tsserverlibrary.js`
12411	`typescript/lib/typescriptServices.js`
12411	`typescript/lib/typescript.js`
12411	`@schematics/angular/third_party/github.com/Microsoft/TypeScript/lib/typescript.js`
10346	`sass/sass.dart.js`
8703	`typescript/lib/typingsInstaller.js`
8528	`typescript/lib/tsc.js`
3933	`@angular/compiler/bundles/compiler.umd.js`
3803	`@angular/compiler/bundles/compiler.umd.min.js`
2602	`selenium-webdriver/lib/test/data/js/tinymce.min.js`
2264	`@angular/core/bundles/core.umd.js`
2028	`@angular/core/bundles/core.umd.min.js`
1457	`terser/dist/bundle.min.js`
1416	`rxjs/bundles/rxjs.umd.js`
1416	`@angular-devkit/schematics/node_modules/rxjs/bundles/rxjs.umd.js`
1416	`@angular-devkit/core/node_modules/rxjs/bundles/rxjs.umd.js`
1416	`@angular-devkit/build-webpack/node_modules/rxjs/bundles/rxjs.umd.js`
1416	`@angular-devkit/build-angular/node_modules/rxjs/bundles/rxjs.umd.js`
1416	`@angular-devkit/architect/node_modules/rxjs/bundles/rxjs.umd.js`

What about the production js bundle?

Nothing really interesting. The Webpack works efficiently. 95% functions are unique of the 1282 used. Here are top five functions that have duplicates:

quantity	function
11	`const z=function(){};`
10	`const z=()=>R;`
8	`const z=function(n){return new(n\|\|t)};`
6	`const z=function(n){};`
5	`const z=()=>{};`

What about React?

I also checked React. I put the comparison in the table below:

In the `node_modules`	Angular	React
total * .js files	26982	23942
total functions	338230	163385
unique functions	130886	92766
% of unique functions	39%	57%

You can download the csv file for self-checking here.

Top 20 most popular functions in `node_modules` for the React project

The react project was generated by create-react-app my-app. The files package.json and yarn.lock are here.

#	id	number of duplicates
1	12f746f2689073d5c949998e0216f68a	1377
2	285d00ca29fcc46aa113c7aefc63827d	1243
3	3f993321f73e83f277c20c178e5587b9	989
4	54782ec6cef850906484808b86946b33	299
5	7d1e7aad635be0f7382696c4f846beae	278
6	d11004e998280b565ad084b0ad5ca214	239
7	a02c66d8928b3353552e4804c6714326	237
8	79e9bd3cdf15cf0af97f73ccaed50fa0	231
9	7d6f69751712ef9fa94238b38120adc6	189
10	b8dd34af96b042c23a4be7f82c881fe4	176
11	863a48e36413feba8bb299623dbc9b20	174
12	2482d2afd404031c67adb9cbc012768b	174
13	4728096fca2b3575800dafbdebf4276a	170
14	bf8b05684375b26205e50fa27317057e	157
15	fd114ee6b71ee06738b5b547b00e8102	156
16	df1c43e5a72e92d11bdefcead13a5e14	156
17	094afc30995ff28993ec5326e8b3c4d4	156
18	042490db7093660e74a762447f64f950	156
19	5c5979ec3533f13b22153de05ffc64d5	154
20	50645492c50621c0847c4ebd1fdd65cd	154

12f746f2689073d5c949998e0216f68a, 1377 identical, function names usually: _interopRequireDefault
```
function MORK(e){return e&&e.__esModule?e:{default:e}}
```
285d00ca29fcc46aa113c7aefc63827d, 1243 identical
```
const z=function(){};
```
3f993321f73e83f277c20c178e5587b9, 989 identical
```
const z=function(){return data};
```
54782ec6cef850906484808b86946b33, 299 identical
```
const z=()=>{};
```
7d1e7aad635be0f7382696c4f846beae, 278 identical, function names: emptyFunction, Generator
```
function MORK(){}
```
d11004e998280b565ad084b0ad5ca214, 239 identical
```
const z=function(){return cache};
```

a02c66d8928b3353552e4804c6714326, 237 identical, function names: _getRequireWildcardCache

function MORK(){if("function"!=typeof WeakMap)return null;var e=new WeakMap;return _getRequireWildcardCache=function(){return e},e}

79e9bd3cdf15cf0af97f73ccaed50fa0, 231 identical, function names _interopRequireWildcard

function MORK(e){if(e&&e.__esModule)return e;if(null===e||"object"!=typeof e&&"function"!=typeof e)return{default:e};var t=_getRequireWildcardCache();if(t&&t.has(e))return t.get(e);var r,n,o={},c=Object.defineProperty&&Object.getOwnPropertyDescriptor;for(r in e)Object.prototype.hasOwnProperty.call(e,r)&&((n=c?Object.getOwnPropertyDescriptor(e,r):null)&&(n.get||n.set)?Object.defineProperty(o,r,n):o[r]=e[r]);return o.default=e,t&&t.set(e,o),o}

7d6f69751712ef9fa94238b38120adc6, 189 identical
```
const z=function(){return this};
```

b8dd34af96b042c23a4be7f82c881fe4, 176 identical

const z=function(n,o,c,i){n[i=void 0===i?c:i]=o[c]};

863a48e36413feba8bb299623dbc9b20, 174 identical

const z=function(e,n,t,o){void 0===o&&(o=t),Object.defineProperty(e,o,{enumerable:!0,get:function(){return n[t]}})};

2482d2afd404031c67adb9cbc012768b, 174 identical
```
const z=function(){return m[k]};
```
4728096fca2b3575800dafbdebf4276a, 170 identical
```
const z=function(n){return n};
```
bf8b05684375b26205e50fa27317057e, 157 identical
```
const z=s=>exposed.has(s);
```

fd114ee6b71ee06738b5b547b00e8102, 156 identical

const z=(r,e,p)=>{var t=makeWrapper(r);return exports.setup(t,r,e,p)};

df1c43e5a72e92d11bdefcead13a5e14, 156 identical

const z=t=>utils.isObject(t)&&t instanceof Impl.implementation;

094afc30995ff28993ec5326e8b3c4d4, 156 identical

const z=i=>utils.isObject(i)&&utils.hasOwn(i,implSymbol)&&i[implSymbol]instanceof Impl.implementation;

042490db7093660e74a762447f64f950, 156 identical

const z=(r,e,t)=>{t=exports.create(r,e,t);return utils.implForWrapper(t)};

5c5979ec3533f13b22153de05ffc64d5, 154 identical

const z=function(e){if(e&&e.__esModule)return e;var t={};if(null!=e)for(var r in e)"default"!==r&&Object.prototype.hasOwnProperty.call(e,r)&&__createBinding(t,e,r);return __setModuleDefault(t,e),t};

50645492c50621c0847c4ebd1fdd65cd, 154 identical

const z=function(e,n){Object.defineProperty(e,"default",{enumerable:!0,value:n})};

Which files use function 8 (79e9bd3cdf15cf0af97f73ccaed50fa0)

View file list

The list is long

/jest-worker/build/base/BaseWorkerPool.js
/@svgr/hast-util-to-babel-ast/lib/index.js
/@svgr/hast-util-to-babel-ast/lib/handlers.js
/@svgr/hast-util-to-babel-ast/lib/stringToObjectStyle.js
/@svgr/hast-util-to-babel-ast/lib/getAttributes.js
/babel-jest/node_modules/@babel/core/lib/transform-file.js
/babel-jest/node_modules/@babel/core/lib/config/files/configuration.js
/babel-jest/node_modules/@babel/core/lib/config/files/utils.js
/babel-jest/node_modules/@babel/core/lib/config/full.js
/babel-jest/node_modules/@babel/core/lib/transformation/normalize-file.js
/babel-jest/node_modules/@babel/core/lib/transformation/file/file.js
/babel-jest/node_modules/@babel/core/lib/tools/build-external-helpers.js
/babel-jest/node_modules/@babel/core/lib/index.js
/jest-pnp-resolver/node_modules/jest-resolve/build/defaultResolver.js
/jest-pnp-resolver/node_modules/jest-resolve/build/ModuleNotFoundError.js
/jest-circus/build/utils.js
/jest-haste-map/build/ModuleMap.js
/jest-haste-map/build/lib/normalizePathSep.js
/jest-haste-map/build/lib/fast_path.js
/jest-haste-map/build/lib/WatchmanWatcher.js
/jest-haste-map/build/worker.js
/jest-haste-map/build/getMockName.js
/jest-haste-map/build/HasteFS.js
/jest-haste-map/build/crawlers/watchman.js
/jest-jasmine2/build/index.js
/eslint/node_modules/@babel/code-frame/lib/index.js
/mini-css-extract-plugin/dist/index.js
/react-scripts/node_modules/@babel/core/lib/transform-file.js
/react-scripts/node_modules/@babel/core/lib/config/files/configuration.js
/react-scripts/node_modules/@babel/core/lib/config/files/utils.js
/react-scripts/node_modules/@babel/core/lib/config/full.js
/react-scripts/node_modules/@babel/core/lib/transformation/normalize-file.js
/react-scripts/node_modules/@babel/core/lib/transformation/file/file.js
/react-scripts/node_modules/@babel/core/lib/tools/build-external-helpers.js
/react-scripts/node_modules/@babel/core/lib/index.js
/react-scripts/node_modules/jest-resolve/build/defaultResolver.js
/react-scripts/node_modules/jest-resolve/build/ModuleNotFoundError.js
/eslint-plugin-flowtype/dist/utilities/index.js
/jest-util/build/index.js
/jest-util/build/createDirectory.js
/jest-util/build/installCommonGlobals.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx-development/node_modules/@babel/core/lib/transform-file.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx-development/node_modules/@babel/core/lib/config/files/configuration.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx-development/node_modules/@babel/core/lib/config/files/utils.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx-development/node_modules/@babel/core/lib/config/full.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx-development/node_modules/@babel/core/lib/transformation/normalize-file.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx-development/node_modules/@babel/core/lib/transformation/file/file.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx-development/node_modules/@babel/core/lib/tools/build-external-helpers.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx-development/node_modules/@babel/core/lib/index.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-pure-annotations/node_modules/@babel/core/lib/transform-file.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-pure-annotations/node_modules/@babel/core/lib/config/files/configuration.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-pure-annotations/node_modules/@babel/core/lib/config/files/utils.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-pure-annotations/node_modules/@babel/core/lib/config/full.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-pure-annotations/node_modules/@babel/core/lib/transformation/normalize-file.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-pure-annotations/node_modules/@babel/core/lib/transformation/file/file.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-pure-annotations/node_modules/@babel/core/lib/tools/build-external-helpers.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-pure-annotations/node_modules/@babel/core/lib/index.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx/node_modules/@babel/core/lib/transform-file.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx/node_modules/@babel/core/lib/config/files/configuration.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx/node_modules/@babel/core/lib/config/files/utils.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx/node_modules/@babel/core/lib/config/full.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx/node_modules/@babel/core/lib/transformation/normalize-file.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx/node_modules/@babel/core/lib/transformation/file/file.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx/node_modules/@babel/core/lib/tools/build-external-helpers.js
/babel-preset-react-app/node_modules/@babel/plugin-transform-react-jsx/node_modules/@babel/core/lib/index.js
/babel-preset-react-app/node_modules/@babel/preset-env/node_modules/@babel/plugin-proposal-class-properties/node_modules/@babel/core/lib/transform-file.js
/babel-preset-react-app/node_modules/@babel/preset-env/node_modules/@babel/plugin-proposal-class-properties/node_modules/@babel/core/lib/config/files/configuration.js
/babel-preset-react-app/node_modules/@babel/preset-env/node_modules/@babel/plugin-proposal-class-properties/node_modules/@babel/core/lib/config/files/utils.js
/babel-preset-react-app/node_modules/@babel/preset-env/node_modules/@babel/plugin-proposal-class-properties/node_modules/@babel/core/lib/config/full.js
/babel-preset-react-app/node_modules/@babel/preset-env/node_modules/@babel/plugin-proposal-class-properties/node_modules/@babel/core/lib/transformation/normalize-file.js
/babel-preset-react-app/node_modules/@babel/preset-env/node_modules/@babel/plugin-proposal-class-properties/node_modules/@babel/core/lib/transformation/file/file.js
/babel-preset-react-app/node_modules/@babel/preset-env/node_modules/@babel/plugin-proposal-class-properties/node_modules/@babel/core/lib/tools/build-external-helpers.js
/babel-preset-react-app/node_modules/@babel/preset-env/node_modules/@babel/plugin-proposal-class-properties/node_modules/@babel/core/lib/index.js
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Сonclusions?

Perhaps this little research will give someone thoughts about refactoring. Or changing the programming approach.

It is good that people use some common approaches and patterns for programming.

It's bad that there is a lot of copy-paste.

P.S.

Used scripts can be found on GitHub

Only 39% of the functions in node_modules are unique in the default Angular project