Over the years as a programmer, I've looked at perhaps hundreds of codebases. Too many to be accurate. I struggled a lot with understanding where the meaningful code is in most cases. Usually, a request for guidance on what I should pay attention to, and the instructions in the tickets push me forward. Slowly but surely, I will understand what the code is doing. And you will understand too. Some people do it better, and some people do it slowly. You shouldn't be ashamed of this. In most cases, the code is complex. But I found a simple tool to make things easier for you.It's called code-complexity and you can use it like
this:
npx code-complexity . --limit 20 --sort ratio # --filter '**/*.js',
It will print output similar to this:
| file | complexity | churn | ratio |
|---|---|---|---|
| src / cli.ts | 103 | 8 | 824 |
| test / code-complexity.test.ts | 107 | 7 | 749 |
| .idea / workspace.xml | 123 | 6 | 738 |
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npx code-complexity . --limit 20 --sort ratio
| file | complexity | churn | ratio |
|---|---|---|---|
| nextjs/packages/next/compiled/webpack/bundle5.js | 91501 | 1 | 91501 |
| nextjs/packages/next/compiled/webpack/bundle5.js | 91501 | 1 | 91501 |
| nextjs/packages/next/compiled/webpack/bundle4.js | 74436 | 1 | 74436 |
| packages/cli/src/commands/generate.ts | 228 | 28 | 6384 |
| packages/cli/src/commands/new.ts | 177 | 35 | 6195 |
| packages/generator/src/generators/app-generator.ts | 235 | 23 | 5405 |
| packages/generator/src/generator.ts | 283 | 19 | 5377 |
| packages/server/src/stages/rpc/index.ts | 184 | 28 | 5152 |
| packages/server/test/dev.test.ts | 190 | 27 | 5130 |
| packages/core/src/types.ts | 160 | 28 | 4480 |
| packages/server/src/next-utils.ts | 176 | 25 | 4400 |
| packages/generator/templates/app/app/pages/index.tsx | 240 | 18 | 4320 |
| packages/server/src/config.ts | 116 | 37 | 4292 |
| packages/core/src/use-query-hooks.ts | 184 | 22 | 4048 |
| nextjs/test/integration/file-serving/test/index.test.js | 3561 | 1 | 3561 |
| examples/auth/app/pages/index.tsx | 210 | 16 | 3360 |
| packages/cli/src/commands/db.ts | 75 | 44 | 3300 |
| .github/workflows/main.yml | 132 | 24 | 3168 |
| packages/cli/test/commands/new.test.ts | 141 | 19 | 2679 |
| examples/store/app/pages/index.tsx | 181 | 14 | 2534 |
| packages/display/src/index.ts | 158 | 16 | 2528 |
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npx code-complexity . --limit 20 --sort ratio
:
| file | complexity | churn | ratio |
|---|---|---|---|
| packages/eslint-plugin-react-hooks/**tests**/ESLintRuleExhaustiveDeps-test.js | 7742 | 51 | 394842 |
| packages/react/src/**tests**/ReactProfiler-test.internal.js | 4002 | 95 | 380190 |
| packages/react-reconciler/src/ReactFiberWorkLoop.new.js | 2373 | 139 | 329847 |
| packages/react-reconciler/src/ReactFiberWorkLoop.old.js | 2373 | 114 | 270522 |
| packages/react-dom/src/server/ReactPartialRenderer.js | 1379 | 122 | 168238 |
| packages/react-reconciler/src/ReactFiberCommitWork.new.js | 2262 | 71 | 160602 |
| packages/react-devtools-shared/src/backend/renderer.js | 2952 | 54 | 159408 |
| packages/react-reconciler/src/ReactFiberBeginWork.new.js | 2903 | 53 | 153859 |
| scripts/rollup/bundles.js | 760 | 199 | 151240 |
| packages/react-reconciler/src/ReactFiberHooks.new.js | 2622 | 56 | 146832 |
| packages/react-dom/src/client/ReactDOMHostConfig.js | 1018 | 140 | 142520 |
| packages/react-reconciler/src/ReactFiberHooks.old.js | 2622 | 50 | 131100 |
| packages/react-reconciler/src/**tests**/ReactHooks-test.internal.js | 1641 | 74 | 121434 |
| packages/react-dom/src/**tests**/ReactDOMComponent-test.js | 2346 | 51 | 119646 |
| packages/react-dom/src/**tests**/ReactDOMServerPartialHydration-test.internal.js | 2150 | 49 | 105350 |
| packages/react-noop-renderer/src/createReactNoop.js | 966 | 109 | 105294 |
| packages/react-reconciler/src/ReactFiberCommitWork.old.js | 2262 | 46 | 104052 |
| packages/react-reconciler/src/ReactFiberBeginWork.old.js | 2903 | 35 | 101605 |
| packages/react-reconciler/src/**tests**/ReactIncrementalErrorHandling-test.internal.js | 1532 | 62 | 94984 |
| packages/react-refresh/src/**tests**/ReactFresh-test.js | 3165 | 29 | 91785 |
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npx code-complexity . --limit 20 --sort ratio
| file | complexity | churn | ratio |
|---|---|---|---|
| src/lib/jsQR/jsQR.js | 9760 | 5 | 48800 |
| src/lib/wapi/wapi.js | 474 | 44 | 20856 |
| src/api/layers/sender.layer.ts | 546 | 36 | 19656 |
| src/lib/wapi/store/store-objects.js | 362 | 24 | 8688 |
| src/controllers/initializer.ts | 178 | 48 | 8544 |
| src/lib/wapi/jssha/index.js | 1204 | 5 | 6020 |
| src/api/layers/retriever.layer.ts | 171 | 29 | 4959 |
| src/types/WAPI.d.ts | 203 | 24 | 4872 |
| src/api/layers/host.layer.ts | 258 | 17 | 4386 |
| src/api/layers/listener.layer.ts | 206 | 21 | 4326 |
| src/controllers/browser.ts | 141 | 29 | 4089 |
| src/controllers/auth.ts | 192 | 21 | 4032 |
| src/api/model/enum/definitions.ts | 589 | 6 | 3534 |
| src/api/whatsapp.ts | 95 | 30 | 2850 |
| src/lib/wapi/functions/index.js | 97 | 24 | 2328 |
| src/api/layers/profile.layer.ts | 82 | 22 | 1804 |
| src/lib/wapi/business/send-message-with-buttons.js | 323 | 5 | 1615 |
| src/api/layers/group.layer.ts | 115 | 14 | 1610 |
| src/api/layers/controls.layer.ts | 76 | 20 | 1520 |
| src/api/model/message.ts | 114 | 11 | 1254 |
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I hope you enjoyed this article and made your life a little easier. Getting into a new codebase is tricky, and especially in the ever-changing world of JavaScript, it's hard to keep up. With the tools and processes presented in this article, you might find it easier to fit into the new codebase. Feel free to share this article with your colleagues and also tell them about the techniques you are using. Most of the developers I know don't know about flow and complexity analysis, and it can be very useful for everyone. So share it!