last

function last<T>(array: T[]): T | undefined;
function last<T>(array: T[], n: number): T[];
function last<T>(array: T[], n?: number): T | T[] | undefined;

This is what array[array.length - 1] is written for — an expression that yields undefined on an empty array while looking like it meant something else. last says it plainly and returns undefined in the same case.

The n form takes from the end but preserves the original order: last([1, 2, 3], 2) is [2, 3], not [3, 2]. n is clamped, so a negative count yields an empty array and a count beyond the length yields the whole array. The input is not modified.

Parameters

Parameter	Type	Description
`array`	`T[]`	The array to read from. Left untouched.
`n` (optional)	`number`	How many elements to take. An integer; omit it to take a single one.

Returns

T | T[] | undefined — T | undefined when n is omitted — the last element, or undefined for an empty array. T[] when n is given — a new array of at most n elements, in their original order.

Throws

Exception	Condition
`TypeError`	`array` is not an array.
`TypeError`	`n` is given and is not an integer.

Examples

One element, or several

last([1, 2, 3]); // => 3
last([]); // => undefined
last([1, 2, 3], 2); // => [2, 3] — order preserved

Reading the most recent entries of a log sheet

/**
 * Logs the ten newest entries of a log sheet, oldest of the ten first.
 */
export function logRecentEntries(sheet: GoogleAppsScript.Spreadsheet.Sheet): void {
  const rows = sheet.getDataRange().getValues().slice(1);

  for (const row of last(rows, 10)) {
    Logger.log(row.join(" | "));
  }
}

function logRecentEntries(sheet) {
  const rows = sheet.getDataRange().getValues().slice(1);
  for (const row of last(rows, 10)) {
    Logger.log(row.join(" | "));
  }
}

Clamping

last([1, 2], 10); // => [1, 2]
last([1, 2], -1); // => []
last([1, 2], 1.5); // throws TypeError: Input 'n' must be an integer.

Source

src/lang/array/last.ts

23 September 2026

This documentation was generated with AI (Claude) from the library's source code.

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