fileReadJSONBuffers

Prefer reading JSON files as buffers when using JSON.parse for better performance.

✅ This rule is included in the node stylistic preset.

JSON.parse() can parse buffers directly without needing to convert them to strings first. Reading files as buffers when parsing JSON avoids unnecessary string conversion overhead.

When reading a JSON file with fs.readFile() or fs.readFileSync() and then parsing it with JSON.parse(), there’s no need to specify UTF-8 encoding. The file can be read as a buffer, and JSON.parse() will handle the buffer directly.

Examples

❌ Incorrect

const packageJson = JSON.parse(await fs.readFile("./package.json", "utf8"));

const data = JSON.parse(await fs.readFile("./data.json", "utf-8"));

const config = JSON.parse(fs.readFileSync("./config.json", "utf8"));

const settings = JSON.parse(
  fs.readFileSync("./settings.json", { encoding: "utf-8" }),
);

✅ Correct

const packageJson = JSON.parse(await fs.readFile("./package.json"));

const data = JSON.parse(await fs.readFile("./data.json"));

const config = JSON.parse(fs.readFileSync("./config.json"));

const settings = JSON.parse(fs.readFileSync("./settings.json"));

Options

This rule is not configurable.

When Not To Use It

If you explicitly prefer to always describe encoding parameters, this rule might not be for you. Additionally, if you choose to manually choose which nuanced parsing behavior you prefer, you may disagree with this rule and choose not to enable it.

Further Reading

• Node.js: JSON.parse()
• Node.js: fs.readFile()
• MDN: JSON.parse()

Equivalents in Other Linters

• ESLint: unicorn/prefer-json-parse-buffer