Returns the last element in an array.
Check if arr
is truthy and has a length
property, use arr.length - 1
to compute the index of the last element of the given array and return it, otherwise return undefined
.
代码片段
const last = arr => (arr && arr.length ? arr[arr.length - 1] : undefined);
使用样例
last([1, 2, 3]); // 3
last([]); // undefined
last(null); // undefined
last(undefined); // undefined