Rule: no-for-in-array

Disallows iterating over an array with a for-in loop.

A for-in loop (for (var k in o)) iterates over the properties of an Object.

While it is legal to use for-in loops with array types, it is not common. for-in will iterate over the indices of the array as strings, omitting any “holes” in the array.

More common is to use for-of, which iterates over the values of an array. If you want to iterate over the indices, alternatives include:

array.forEach((value, index) => { … }); for (const [index, value] of array.entries()) { … } for (let i = 0; i < array.length; i++) { … }

Notes:

Config

Not configurable.

Config examples

"no-for-in-array": true

Schema

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