arrayIncludesMethods

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

✅ This rule is included in the ts stylistic and stylisticStrict 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().

declare const 
const array: string[]
array: string[];
const array: string[]
array.
Array<string>.some(predicate: (value: string, index: number, array: string[]) => unknown, thisArg?: any): boolean
Determines whether the specified callback function returns true for any element of an array.
@param ― predicate A function that accepts up to three arguments. The some method calls
the predicate function for each element in the array until the predicate returns a value
which is coercible to the Boolean value true, or until the end of the array.
@param ― thisArg An object to which the this keyword can refer in the predicate function.
If thisArg is omitted, undefined is used as the this value.
some((
item: string
item) => 
item: string
item === "value");

declare const 
const array: string[]
array: string[];
const array: string[]
array.
Array<string>.some(predicate: (value: string, index: number, array: string[]) => unknown, thisArg?: any): boolean
Determines whether the specified callback function returns true for any element of an array.
@param ― predicate A function that accepts up to three arguments. The some method calls
the predicate function for each element in the array until the predicate returns a value
which is coercible to the Boolean value true, or until the end of the array.
@param ― thisArg An object to which the this keyword can refer in the predicate function.
If thisArg is omitted, undefined is used as the this value.
some((
item: string
item) => "value" === 
item: string
item);

declare const 
const array: number[]
array: number[];
declare const 
const target: number
target: number;
const array: number[]
array.
Array<number>.some(predicate: (value: number, index: number, array: number[]) => unknown, thisArg?: any): boolean
Determines whether the specified callback function returns true for any element of an array.
@param ― predicate A function that accepts up to three arguments. The some method calls
the predicate function for each element in the array until the predicate returns a value
which is coercible to the Boolean value true, or until the end of the array.
@param ― thisArg An object to which the this keyword can refer in the predicate function.
If thisArg is omitted, undefined is used as the this value.
some((
element: number
element) => 
element: number
element === 
const target: number
target);

declare const 
const array: string[]
array: string[];
const array: string[]
array.
Array<string>.some(predicate: (value: string, index: number, array: string[]) => unknown, thisArg?: any): boolean
Determines whether the specified callback function returns true for any element of an array.
@param ― predicate A function that accepts up to three arguments. The some method calls
the predicate function for each element in the array until the predicate returns a value
which is coercible to the Boolean value true, or until the end of the array.
@param ― thisArg An object to which the this keyword can refer in the predicate function.
If thisArg is omitted, undefined is used as the this value.
some(function (
item: string
item) {
  return 
item: string
item === "value";
});

declare const 
const array: string[]
array: string[];
const array: string[]
array.
Array<string>.includes(searchElement: string, fromIndex?: number): boolean
Determines whether an array includes a certain element, returning true or false as appropriate.
@param ― searchElement The element to search for.
@param ― fromIndex The position in this array at which to begin searching for searchElement.
includes("value");

declare const 
const array: string[]
array: string[];
const array: string[]
array.
Array<string>.some(predicate: (value: string, index: number, array: string[]) => unknown, thisArg?: any): boolean
Determines whether the specified callback function returns true for any element of an array.
@param ― predicate A function that accepts up to three arguments. The some method calls
the predicate function for each element in the array until the predicate returns a value
which is coercible to the Boolean value true, or until the end of the array.
@param ― thisArg An object to which the this keyword can refer in the predicate function.
If thisArg is omitted, undefined is used as the this value.
some((
item: string
item) => 
item: string
item.
String.startsWith(searchString: string, position?: number): boolean
Returns true if the sequence of elements of searchString converted to a String is the
same as the corresponding elements of this object (converted to a String) starting at
position. Otherwise returns false.
startsWith("v"));

declare const 
const array: number[]
array: number[];
const array: number[]
array.
Array<number>.some(predicate: (value: number, index: number, array: number[]) => unknown, thisArg?: any): boolean
Determines whether the specified callback function returns true for any element of an array.
@param ― predicate A function that accepts up to three arguments. The some method calls
the predicate function for each element in the array until the predicate returns a value
which is coercible to the Boolean value true, or until the end of the array.
@param ― thisArg An object to which the this keyword can refer in the predicate function.
If thisArg is omitted, undefined is used as the this value.
some((
item: number
item) => 
item: number
item > 0);

declare const 
const array: object[]
array: object[];
const array: object[]
array.
Array<object>.some(predicate: (value: object, index: number, array: object[]) => unknown, thisArg?: any): boolean
Determines whether the specified callback function returns true for any element of an array.
@param ― predicate A function that accepts up to three arguments. The some method calls
the predicate function for each element in the array until the predicate returns a value
which is coercible to the Boolean value true, or until the end of the array.
@param ― thisArg An object to which the this keyword can refer in the predicate function.
If thisArg is omitted, undefined is used as the this value.
some((
item: object
item) => 
item: object
item.
any
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.

Equivalents in Other Linters

ESLint: unicorn/prefer-includes

Made with ❤️‍🔥 around the world by the Flint team and contributors.

arrayIncludesMethods

Examples

Options

When Not To Use It

Further Reading

Equivalents in Other Linters