atAccesses

Prefer using .at() for accessing elements at negative indices.

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

Accessing an element at the end of an array or string using array[array.length - 1] is less readable than using the .at() method with a negative index. The .at() method provides a cleaner syntax for accessing elements from the end of a sequence.

const 
const last: number
last = 
const array: number[]
array[
const array: number[]
array.
Array<number>.length: number
Gets or sets the length of the array. This is a number one higher than the highest index in the array.
length - 1];

const 
const secondLast: string
secondLast = 
const items: string[]
items[
const items: string[]
items.
Array<string>.length: number
Gets or sets the length of the array. This is a number one higher than the highest index in the array.
length - 2];

const 
const lastChar: string
lastChar = 
const text: string
text[
const text: string
text.
String.length: number
Returns the length of a String object.
length - 1];

const 
const last: number | undefined
last = 
const array: number[]
array.
Array<number>.at(index: number): number | undefined
Returns the item located at the specified index.
@param ― index The zero-based index of the desired code unit. A negative index will count back from the last item.
at(-1);

const 
const secondLast: string | undefined
secondLast = 
const items: string[]
items.
Array<string>.at(index: number): string | undefined
Returns the item located at the specified index.
@param ― index The zero-based index of the desired code unit. A negative index will count back from the last item.
at(-2);

const 
const lastChar: string | undefined
lastChar = 
const text: string
text.
String.at(index: number): string | undefined
Returns a new String consisting of the single UTF-16 code unit located at the specified index.
@param ― index The zero-based index of the desired code unit. A negative index will count back from the last item.
at(-1);

const 
const first: number
first = 
const array: number[]
array[0];

const 
const element: number
element = 
const array: number[]
array[
const dynamicIndex: number
dynamicIndex];

Options

This rule is not configurable.

When Not To Use It

If you need to support environments that do not have the .at() method (pre-ES2022), or if your project has a polyfill that only covers certain cases, you can disable this rule.

Equivalents in Other Linters

Biome: useAtIndex
ESLint: unicorn/prefer-at

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atAccesses

Examples

Options

When Not To Use It

Further Reading

Equivalents in Other Linters