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unicorn/text-encoding-identifier-case Style

🛠️ An auto-fix is available for this rule.

What it does

This rule enforces consistent casing for text encoding identifiers, specifically:

• 'utf8' instead of 'UTF-8' or 'utf-8' (or 'utf-8' if withDash is enabled)
• 'ascii' instead of 'ASCII'

Why is this bad?

Inconsistent casing of encoding identifiers reduces code readability and can lead to subtle confusion across a codebase. Although casing is not strictly enforced by ECMAScript or Node.js, using lowercase is the conventional and widely recognized style.

Examples

Examples of incorrect code for this rule:

import fs from "node:fs/promises";
async function bad() {
  await fs.readFile(file, "UTF-8");
  await fs.readFile(file, "ASCII");
  const string = buffer.toString("utf-8");
}

Examples of correct code for this rule:

import fs from "node:fs/promises";
async function good() {
  await fs.readFile(file, "utf8");
  await fs.readFile(file, "ascii");
  const string = buffer.toString("utf8");
}

Examples of correct code for this rule with { "withDash": true }:

import fs from "node:fs/promises";
async function good() {
  await fs.readFile(file, "utf-8");
  await fs.readFile(file, "ascii");
  const string = buffer.toString("utf-8");
}

Configuration

This rule accepts a configuration object with the following properties:

withDash

type: boolean

default: false

If true, prefer utf-8 over utf8.

How to use

To enable this rule using the config file or in the CLI, you can use:

Config (.oxlintrc.json)

{
  "rules": {
    "unicorn/text-encoding-identifier-case": "error"
  }
}

CLI

oxlint --deny unicorn/text-encoding-identifier-case

References

• Rule Source