Enforce global constants adhere to a pattern (global-constant-pattern)

This rule enforces that global literal, array, object and binary expression constants as well as constants that got an identifier assigned are ALL_CAPS_SNAKE_CASE.

🔧 The --fix option on the command line renames these constants to adhere to the pattern taking existing snake and camel casing into account (someGlobalConstant => SOME_GLOBAL_CONSTANT)

In version 3.0.2 the fix option for this rule has been switched off temporarily as it was a bit too enthousiastic on occasion. It might return in a future version.

Rule Details

Examples of incorrect code for this rule:

// global const literals should be in upper case
// b.t.w. the fixer corrects this to THIS_IS_A_GLOBAL_CONST
const thisIsAGlobalConst = "but it looks like a variable";

// multi const declaration with lower case only
const snakes_but_no_caps = 1,
  secondconstant = 2;

// also assignments of arrays and objects to a global constant
// are subject to this rule
const thisIsAnArray = ["aap", "noot", "mies", "wim", "zus"];

const severity2coolness = {
  info: "cool",
  warn: "not cool - fix later",
  error: "very uncool - fix now",
};

// ass well as binary expressions:
const dayInSeconds = 24 * 60 * 60;

// ... and identifiers
const jourEnSecondes = dayInSeconds;

// the rule also extends to exported constants
export const exportedGlobalConst = "something";

Examples of correct code for this rule:

// upper case as it's an assignment of a literal to a global constant
const GLOBAL_CONSTANT = 123;

// also in multi const declarations
const MULTIPLE = 1,
  CONSTANTS = 2,
  IN_ONE_DECLARATION = 3;

// upper case is cool for array and object assignments
const THIS_IS_AN_ARRAY = ["aap", "noot", "mies", "wim", "zus"];

const SEVERITY2COOLNESS = {
  info: "cool",
  warn: "not cool - fix later",
  error: "very uncool - fix now",
};

// binary expressions are OK too:
const DAY_IN_SECONDS = 24 * 60 * 60;

// ... and identifiers
const JOUR_EN_SECONDES = DAY_IN_SECONDS;

// exported consts are taken into account as well
export const EXPORTED_GLOBAL_CONST = "something";

// assignments of call expressions to global constants are allowed without
// them having to be snaked upper case.
const _ = require("lodash");
const stateMachineCat = require("state-machine-cat");

// the same for are arrow function expressions
const someFunction = () => {
  return "did stuff";
};

Options

exceptions

Type: array

If you want to allow some global constants names to not adhere to the rule, you can specify these. E.g. if you want to use the constant names π and e, you can do sol like so:

"budapestian/global-constant-pattern": [
  "error",
  { "exceptions": ["π", "e"] }
]

When Not To Use It

• If you don’t want to have this global constant naming convention.
• When you use constant names that contain non-ascii characters from alphabets that don’t have upper and lower case.
  E.g. 参数 will be flagged and cannot be auto corrected a.t.m. However, many non-ascii character sets work out of the box - e.g. константаУлучшение can be auto-corrected. Likewise КОНСТАНТА_УЛУЧШЕНИЕ is valid.
• The fixer doesn’t take variable shadowning/ name masking into account (yet). This is a bad practice anyway because it’s a source of subtle, hard to detect bugs. If you suspect (or don’t know) if you have any shadowed variables switch on eslint core’s no-shadow rule.