last-index-of-x

last-index-of-x

An extended ES6 lastIndexOf.

module.exports(array, searchElement, [fromIndex], [extend]) ⇒ number ⏏

This method returns the last index at which a given element can be found in the array, or -1 if it is not present. The array is searched backwards, starting at fromIndex.

Kind: Exported function
Returns: number - Returns index of found element, otherwise -1.
Throws:

• TypeError If array is null or undefined.

Param	Type	Description
array	Array	The array to search.
searchElement	*	Element to locate in the array.
[fromIndex]	number	The index at which to start searching backwards. Defaults to the array's length minus one, i.e. the whole array will be searched. If the index is greater than or equal to the length of the array, the whole array will be searched. If negative, it is taken as the offset from the end of the array. Note that even when the index is negative, the array is still searched from back to front. If the calculated index is less than 0, -1 is returned, i.e. the array will not be searched.
[extend]	string	Extension type: SameValue or SameValueZero.

Example

import lastIndexOf from 'last-index-of-x';
 
const subject = [NaN, 2, 3, undefined, true, 'hej', null, 2, false, 0, -0];
 
// Standard mode, operates just like `Array.prototype.lastIndexOf`.
lastIndexOf(subject, null); // 6
lastIndexOf(testSubject, '2'); // -1
lastIndexOf(testSubject, NaN); // -1
lastIndexOf(testSubject, 0); // 10
lastIndexOf(testSubject, 2, -6); // 1
 
// `SameValueZero` mode extends `lastIndexOf` to match `NaN`.
lastIndexOf(subject, null, 'SameValueZero'); // 6
lastIndexOf(testSubject, '2', 'SameValueZero'); // -1
lastIndexOf(testSubject, NaN, 'SameValueZero'); // 0
lastIndexOf(testSubject, 0, 'SameValueZero'); // 10
lastIndexOf(testSubject, 2, -6, 'SameValueZero'); // 1
 
// `SameValue` mode extends `lastIndexOf` to match `NaN` and signed `0`.
lastIndexOf(subject, null, 'SameValue'); // 6
lastIndexOf(testSubject, '2', 'SameValue'); // -1
lastIndexOf(testSubject, NaN, 'SameValue'); // 0
lastIndexOf(testSubject, 0, 'SameValue'); // 9
lastIndexOf(testSubject, 2, -6, 'SameValue'); // 1