function getLastElementChild(obj){ if(obj.lastElementChild != undefined){ return obj.lastElementChild; }else{ var nodeLast = obj.lastChild; while(nodeLast && nodeLast.nodeType != 1){ nodeLast = nodeLast.previousSibling; } return nodeLast; } } 1. 2. 3. 4. 5. 6. 7. 8. 9. 10...
ThefindLast()method does not execute the function for empty elements. ThefindLast()method does not change the original array. Array Find Methods: MethodFinds indexOf()The index of the first element with a specified value lastIndexOf()The index of the last element with a specified value ...
* @LastEditors: Do not edit */constdata=[{date:'2021-8-1',income:200},{date:'2021-8-2',income:400},{date:'2021-8-3',income:300},]console.log(`总收入:${data.reduce((pre,currentValue)=>pre+currentValue.income,0)}`);//总收入:900 「二维数组转一位数组」 代码语言:javascript 代...
注意:indexOf 使用strict equality (===操作符基于同样的方法)进行判断 searchElement与数组中包含的元素之间的关系。 Array.prototype.lastIndexOf() 返回数组中最后一个(从右边数第一个)与指定值相等的元素的索引,如果找不到这样的元素,则返回 -1。 4.2.3 迭代方法 在下面的众多遍历方法中,有很多方法都需要指...
用法:arr.includes(searchElement, [fromIndex]) searchElement(必需):要查找的元素 fromIndex(可选):从该索引处开始查找searchElement,如果为负值,则按升序从 array.length + fromIndex 的索引开始搜索。默认为 0。 vararr = [1,2,3,4,5,5];//判断arr数组是否包含了 2vararr1 = arr.includes(2);//从索...
std::cout << "First element: " << arr.front() << std::endl; std::cout << "Last element: " << arr.back() << std::endl; return 0; }使用at 和边界检查实例 #include <iostream> #include <array> int main() { std::array<int, 3> arr = {1, 2, 3}; try { std::cout <...
indexOf()The index of the first element with a specified value lastIndexOf()The index of the last element with a specified value find()The value of the first element that passes a test findIndex()The index of the first element that passes a test ...
34. Find First and Last Position of Element in Sorted Array Given an array of integersnumssorted in ascending order, find the starting and ending position of a giventargetvalue. Your algorithm's runtime complexity must be in the order ofO(logn). ...
Write a JavaScript function to get the last element of an array. Passing the parameter 'n' will return the last 'n' elements of the array. Test Data: console.log(last([7, 9, 0, -2])); console.log(last([7, 9, 0, -2],3)); ...
Array对象允许在一个变量中存储多个值。它存储相同类型元素的固定大小的顺序集合。数组用于存储数据集合,但将数组看作同一类型变量的集合通常更有用。本文主要介绍JavaScript(JS) array.lastIndexOf(searchElement[, fromIndex]) 方法。 原文地址:JavaScript(JS) array.lastIndexOf(searchElement[, fromIndex]) ...