find-last-index.md

[literable].findLastIndex

Searches for an element that matches the conditions defined by a specified predicate, and returns the zero-based index of the last occurrence within the Literable or a portion of it.

Overloads

• findLastIndex(match): Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the entire Literable.
• findLastIndex(match, startIndex): Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the range of elements in the Literable that extends from the first element to the specified index.
• findLastIndex(match, startIndex, count): Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the range of elements in the Literable that contains the specified number of elements and ends at the specified index.

findLastIndex(match)

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the entire Literable.

Parameters

• match: The match function that defines the conditions of the element to search for.
• result: The zero-based index of the last occurrence of an element that matches the conditions defined by match, if found; otherwise, -1.

Examples

The following code example demonstrates how to use the FindLastIndex method to find elements in a collection.

const Literable = require('literable');

const employees = Literable.from([
    { name: 'Frank', id: 2 },
    { name: 'Jill', id: 3 },
    { name: 'Dave', id: 5 },
    { name: 'Jack', id: 8 },
    { name: 'Judith', id: 12 },
    { name: 'Robert', id: 14 },
    { name: 'Adam', id: 1 },
]);

const byJ = employees.findLastIndex(e => e.name.startsWith('J'));
console.log(`'J' starts at index ${byJ}`);

const byJa = employees.findLastIndex(e => e.name.startsWith('Ja'));
console.log(`'Ja' starts at index ${byJa}`);

/*
 The example displays the following output:

 'J' starts at index 4
 'Ja' starts at index 3
*/

findLastIndex(match, startIndex)

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the range of elements in the Literable that extends from the first element to the specified index.

Parameters

• match: The match function that defines the conditions of the element to search for.
• startIndex: The zero-based starting index of the search.
• result: The zero-based index of the last occurrence of an element that matches the conditions defined by match, if found; otherwise, -1.

Examples

The following code example demonstrates how to use the FindLastIndex method to find elements in a collection.

const Literable = require('literable');

const employees = Literable.from([
    { name: 'Frank', id: 2 },
    { name: 'Jill', id: 3 },
    { name: 'Dave', id: 5 },
    { name: 'Jack', id: 8 },
    { name: 'Judith', id: 12 },
    { name: 'Robert', id: 14 },
    { name: 'Adam', id: 1 },
]);

const byJ = employees.findLastIndex(e => e.name.startsWith('J'), 4);
console.log(`'J' starts at index ${byJ}`);

const byJi = employees.findLastIndex(e => e.name.startsWith('Ji'), 4);
console.log(`'Ji' starts at index ${byJi}`);

/*
 The example displays the following output:

 'J' starts at index 4
 'Ji' starts at index 1
*/

findLastIndex(match, startIndex, count)

Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the range of elements in the Literable that contains the specified number of elements and ends at the specified index.

Parameters

• match: The match function that defines the conditions of the element to search for.
• startIndex: The zero-based starting index of the backward search.
• count: The number of elements in the section to search.
• result: The zero-based index of the first occurrence of an element that matches the conditions defined by match, if found; otherwise, -1.

Examples

The following code example demonstrates how to use the FindLastIndex method to find elements in a collection.

const Literable = require('literable');

const employees = Literable.from([
    { name: 'Frank', id: 2 },
    { name: 'Jill', id: 3 },
    { name: 'Dave', id: 5 },
    { name: 'Jack', id: 8 },
    { name: 'Judith', id: 12 },
    { name: 'Robert', id: 14 },
    { name: 'Adam', id: 1 },
]);

const byJa = employees.findLastIndex(e => e.name.startsWith('Ja'), 4, 3);
console.log(`'Ja' starts at index ${byJa}`);

const byJi = employees.findLastIndex(e => e.name.startsWith('Ji'), 4, 3);
console.log(`'Ji' starts at index ${byJi}`);

/*
 The example displays the following output:

 'Ja' starts at index 3
 'Ji' starts at index -1
*/