unicorn/prefer-response-static-json

new Response(JSON.stringify(data)) sends JSON with the content type text/plain, unless you remember to set the header. Response.json(data) serializes the data and sets Content-Type: application/json for you.

--fix doesn't change the code, because the header changes. --fix-suggestions rewrites the call.

Configure

Off by default. To turn it on:

[lint.rules]
"unicorn/prefer-response-static-json" = "error" # or "warn"

Examples

Reported:

Bun.serve({
  routes: {
    "/user": () => new Response(JSON.stringify({ name: "Ada" })),
    "/missing": () => new Response(JSON.stringify({ error: "not found" }), { status: 404 }),
  },
});

Not reported:

Bun.serve({
  routes: {
    "/user": () => Response.json({ name: "Ada" }),
    "/missing": () => Response.json({ error: "not found" }, { status: 404 }),
  },
});

JSON.stringify() with a replacer or an indent isn't reported, because Response.json() has no way to pass them:

const pretty = new Response(JSON.stringify(report, null, 2));