Younghoon Kim Blog

Feb 21, 20267 min read

Why is Next.js source code so complex? -- The cost of keeping Pages Router

Tracing just next/navigation through the source reveals where the complexity comes from: re-export entry points, context adapters, and .react-server.ts splits.

nextjssource-code

Feb 13, 202616 min read

Minor optimizations found in React source code

Small React source-level optimizations explained: Object.freeze in DEV, Hidden Class effects, branch ordering, and Smi/Double choices.

react

Feb 10, 20268 min read

ESM is asynchronous, so how is static analysis possible?

ESM can be asynchronous and still statically analyzable. This post explains why through the Construction, Instantiation, and Evaluation phases.

javascriptesm+1

Feb 01, 20265 min read

Why Map and Set are known to have better performance than Array

Why Map and Set often outperform Array: hash-based lookup complexity, insertion behavior, and traversal trade-offs including cache locality.

javascriptdata-structure+1

Jan 23, 20264 min read

Measure and improve the performance of the AI tool you created

Rather than judging the quality of AI tools solely by feel, we have a record of quantifying the extent of improvement through datasets and automatic scoring.

aiprompt-smith

Dec 20, 20255 min read

Why bundlers exist

In this article, we summarize why bundlers emerged, what a dependency graph is, and why Vite took a different approach.

bundlervite

Deep Dive intoReact

Recent

Why is Next.js source code so complex? -- The cost of keeping Pages Router

Minor optimizations found in React source code

ESM is asynchronous, so how is static analysis possible?

Archive

Why is Next.js source code so complex? -- The cost of keeping Pages Router

Minor optimizations found in React source code

ESM is asynchronous, so how is static analysis possible?

Why Map and Set are known to have better performance than Array

Measure and improve the performance of the AI tool you created

Why bundlers exist

Why is Next.js source code so complex? -- The cost of keeping Pages Router

Minor optimizations found in React source code

ESM is asynchronous, so how is static analysis possible?

Why is Next.js source code so complex? -- The cost of keeping Pages Router

Minor optimizations found in React source code

ESM is asynchronous, so how is static analysis possible?

Why Map and Set are known to have better performance than Array

Measure and improve the performance of the AI tool you created

Why bundlers exist

Deep Dive intoReact

Recent

Why is Next.js source code so complex? -- The cost of keeping Pages Router

Minor optimizations found in React source code

ESM is asynchronous, so how is static analysis possible?

Archive

Why is Next.js source code so complex? -- The cost of keeping Pages Router

Minor optimizations found in React source code

ESM is asynchronous, so how is static analysis possible?

Why Map and Set are known to have better performance than Array

Measure and improve the performance of the AI ​​tool you created

Why bundlers exist

Why is Next.js source code so complex? -- The cost of keeping Pages Router

Minor optimizations found in React source code

ESM is asynchronous, so how is static analysis possible?

Why is Next.js source code so complex? -- The cost of keeping Pages Router

Minor optimizations found in React source code

ESM is asynchronous, so how is static analysis possible?

Why Map and Set are known to have better performance than Array

Measure and improve the performance of the AI ​​tool you created

Why bundlers exist

Measure and improve the performance of the AI tool you created

Measure and improve the performance of the AI tool you created