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37. Fetch and JSON-RPC Protocols

Low-level node communication without libraries.

1 min read3 questionsup to 50 XPtopic 37/50

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Every EVM node speaks JSON-RPC 2.0 over HTTP POST: sending `{ jsonrpc: "2.0", id, method, params }`. Results or errors arrive in the response body.

js
const res = await fetch(RPC_URL, {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ jsonrpc: "2.0", id: 1, method: "eth_blockNumber", params: [] })
});
const { result, error } = await res.json();

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Check your understanding

  1. 1. What is the standard JSON-RPC version specifier?

  2. 2. Can a JSON-RPC response have HTTP status 200 and still contain an error?

  3. 3. How are numeric outputs encoded in standard EVM RPC results?

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