如何使用 JavaScript 获取数组项中的最后一个元素

Question

I have a list of array items like this:

const items = [
  { a: 1 },
  { b: 2 },
  { c: 3 },
]

How can I return / log the last element: { c: 3 }

Here's what I've tried so far:

let newarray = items.map((item) => {
    console.log(item);
})

console.log(newarray);

Answer 1

只需记录长度减 1，与 es6 无关：

console.log(items[items.length - 1])

Answer 2

If your list has 3 items, the length is 3 but the last item index is 2, since arrays start at 0, so simply do this:

console.log(items[items.length - 1]);

Doc: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array

Answer 3

Update - October 2021 (Chrome 97+)

Proposal for Array.prototype.findLast and Array.prototype.findLastIndex is now on Stage 3!

You can use it like this:

 const items = [ { a: 1 }, { b: 2 }, { c: 3 }, ]; const last_element = items.findLast((item) => true); console.log(last_element);

Answer 4

尝试这个

console.log(items[items.length - 1]);

Answer 5

我想让你尝试不同的东西：

console.log(items.slice(-1));

Answer 6

It's not required to use ES6 to perform the operation you're asking about. You could use either of the following:

/**
 * The last value in the array, `3`, is at the '2' index in the array.
 * To retrieve this value, get the length of the array, '3', and 
 * subtract 1. 
 */
const items = [1, 2, 3];
const lastItemInArray = items[items.length - 1] // => 3

or:

/**
 * Make a copy of the array by calling `slice` (to ensure we don't mutate
 * the original array) and call `pop` on the new array to return the last  
 * value from the new array.
 */
const items = [1, 2, 3];
const lastItemInArray = items.slice().pop(); // => 3

However, if you are dead set on using ES6 to retrieve this value we can leverage the spread operator (which is an ES6 feature) to retrieve the value:

/**
 * Create new array with all values in `items` array. Call `pop` on this 
 * new array to return the last value from the new array.
 *
 * NOTE: if you're using ES6 it might be a good idea to run the code
 * through Babel or some other JavaScript transpiler if you need to
 * support older browsers (IE does not support the spread operator).
 */
const items = [1, 2, 3];
const lastItemInArray = [...items].pop(); // => 3

Answer 7

Update ECMAScript 2021

You can use the Array.at() method introduced in July, 2021

['a','b','c'].at(-1) // 'c'

Further Reading

• Get the last item in an array
• Selecting last element in JavaScript array
• Destructuring to get the last element of an array in es6
• Proposal - Relative Indexing Method
• tc39 spec - Array.at