arrayIncludesMethods

Reports using Array#some() with simple equality checks that can be replaced with .includes().

✅ This rule is included in the ts stylistic presets.

Array.prototype.some() is intended for more complex predicate checks. When the callback only performs a simple equality check (x === value or x == value), .includes() is more readable and expressive.

This rule reports when .some() can be simplified to .includes().

Examples

❌ Incorrect

declare const array: string[];
array.some((item) => item === "value");

declare const array: string[];
array.some((item) => "value" === item);

declare const array: number[];
declare const target: number;
array.some((element) => element === target);

declare const array: string[];
array.some(function (item) {
  return item === "value";
});

✅ Correct

declare const array: string[];
array.includes("value");

declare const array: string[];
array.some((item) => item.startsWith("v"));

declare const array: number[];
array.some((item) => item > 0);

declare const array: object[];
array.some((item) => item.id === 1);

Options

This rule is not configurable.

When Not To Use It

If your codebase uses .some() for consistency even with simple equality checks, or if you have a large number of existing uses that would be difficult to refactor, you might prefer to disable this rule.

Further Reading

• MDN: Array.prototype.includes()
• MDN: Array.prototype.some()

Equivalents in Other Linters

• ESLint: unicorn/prefer-includes