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Fix grammar and clarity issues in Array.prototype.indexOf documentation #42146

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Fix grammar and clarity issues in Array.prototype.indexOf documentation #42146

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9 changes: 4 additions & 5 deletions files/en-us/web/javascript/reference/global_objects/array/indexof/index.md
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Expand Up @@ -7,8 +7,7 @@ browser-compat: javascript.builtins.Array.indexOf
sidebar: jsref
---

The **`indexOf()`** method of {{jsxref("Array")}} instances returns the first index at which a
given element can be found in the array, or -1 if it is not present.
The **`indexOf()`** method of {{jsxref("Array")}} instances returns the first index at which an element can be found in the array, or -1 if it is not present.

{{InteractiveExample("JavaScript Demo: Array.prototype.indexOf()")}}

Expand Down Expand Up @@ -36,10 +35,10 @@ indexOf(searchElement, fromIndex)
### Parameters

- `searchElement`
- : Element to locate in the array.
- : The element to locate in the array.
- `fromIndex` {{optional_inline}}
- : Zero-based index at which to start searching, [converted to an integer](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number#integer_conversion).
- Negative index counts back from the end of the array — if `-array.length <= fromIndex < 0`, `fromIndex + array.length` is used. Note, the array is still searched from front to back in this case.
- Negative index counts back from the end of the array — if `-array.length <= fromIndex < 0`, `fromIndex + array.length` is used. Note: the array is still searched from front to back in this case.
- If `fromIndex < -array.length` or `fromIndex` is omitted, `0` is used, causing the entire array to be searched.
- If `fromIndex >= array.length`, the array is not searched and `-1` is returned.

Expand All @@ -49,7 +48,7 @@ The first index of `searchElement` in the array; `-1` if not found.

## Description

The `indexOf()` method compares `searchElement` to elements of the array using [strict equality](/en-US/docs/Web/JavaScript/Reference/Operators/Strict_equality) (the same algorithm used by the `===` operator). [`NaN`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/NaN) values are never compared as equal, so `indexOf()` always returns `-1` when `searchElement` is `NaN`.
The `indexOf()` method compares `searchElement` to elements of the array using [strict equality](/en-US/docs/Web/JavaScript/Reference/Operators/Strict_equality) (the same algorithm used by the `===` operator). [`NaN`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/NaN) values are never considered equal, so `indexOf()` always returns `-1` when `searchElement` is `NaN`.

The `indexOf()` method skips empty slots in [sparse arrays](/en-US/docs/Web/JavaScript/Guide/Indexed_collections#sparse_arrays).

Expand Down