QA
Senior LevelReact JS & React 19

How does the React Server Component wire format stream and reconstruct Virtual DOM over HTTP?

❓ Interview Prompt: Explain RSC Wire Format, streaming newline-delimited JSON rows, component IDs, prop references, and client-side Virtual DOM reconstruction.

React Server Components (RSC) do NOT return HTML strings or raw JSON data. They stream a special RSC Wire Format over HTTP:

Wire Format Structure:

Streams newline-delimited JSON rows containing component IDs, serialized props, and Suspense placeholders:

•
'M1:{"id":"./Card.js","name":"Card"}' (Module reference)
•
'J0:["$","div",null,{"children":["$","$L1",null,{}]}]' (Virtual DOM node tree)
•
The client parser streams and reconstructs the Virtual DOM incrementally without using 'eval()'!

Code Implementation Example

jsx
// Example RSC Wire Format streamed over network response:
// M1:{"id":"./Header.client.js","chunks":["client1"],"name":"Header"}
// J0:["$","main",null,{"children":["$","$L1",null,{"title":"Dashboard"}]}]
💡Inspecting raw streamed React Server Component wire format JSON rows.
🎯 Interview Key Takeaway

RSC streams newline-delimited JSON wire format rows, allowing the client to reconstruct the Virtual DOM incrementally while streaming.

#RSC Wire Format#Streaming#RSC#Architecture#Senior
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