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arrayMutableReverses

Reports .reverse() calls on arrays that mutate the original array.

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

The .reverse() method mutates the original array in place. Using .toReversed() instead returns a new reversed array without modifying the original, making code more predictable and avoiding unintended side effects.

Examples

Section titled “Examples”
const 
const values: number[]
values = [1, 2, 3];
const 
const reversed: number[]
reversed = 
const values: number[]
values.
Array<number>.reverse(): number[]
Reverses the elements in an array in place.
This method mutates the array and returns a reference to the same array.
reverse();
const 
const items: string[]
items = ["a", "b", "c"];
const doSomething: any
doSomething(
const items: string[]
items.
Array<string>.reverse(): string[]
Reverses the elements in an array in place.
This method mutates the array and returns a reference to the same array.
reverse());
const 
const data: number[]
data = [1, 2, 3];
const 
const result: number[]
result = [...
const data: number[]
data].
Array<number>.reverse(): number[]
Reverses the elements in an array in place.
This method mutates the array and returns a reference to the same array.
reverse();

Options

Section titled “Options”

This rule is not configurable.

When Not To Use It

Section titled “When Not To Use It”

If you intentionally want to mutate the original array in place, or if you’re working in an environment that doesn’t support .toReversed() (ES2023+), you may want to disable this rule. Note that .reverse() is still allowed when used as a standalone expression statement since the mutation is likely intentional in that case.

Further Reading

Section titled “Further Reading”

Equivalents in Other Linters

Section titled “Equivalents in Other Linters”
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