The standard way to get the total number of elements in an array is to use the built-inlengthproperty: letmyArray = [99,101.5,"John Doe",true, {age:44}];lettotal = myArray.length;console.log(total);// Output: 5// Alternatevly:lettotal = [99,101.5,"John Doe",true, {age:44}...
inArray()方法的基本语法如下: ``` array.indexOf(element, start) array表示要进行查找的数组,element表示要查找的元素,start表示查找起始位置的索引值,需要注意的是,start参数是可选的,如果不指定该参数,则默认从数组的第一个元素开始查找。 二、inArray()方法的返回值 inArray()方法的返回值是一个整数,表示...
log(lastThreeItems); // 输出: [3, 4, 5] 删除数组中的特定元素: 我们使用slice()方法两次来删除数组array1中的第三个元素。首先,我们使用slice(0, 2)来获取索引0到索引2之间的元素(不包括索引2),然后使用concat()方法将其与索引大于2的元素连接起来,从而得到一个新数组newArray。 代码语言:javascript ...
//可以作为参数的可迭代对象有:string、set、map、argumentsconsole.log('array from String', Array.from('abc'))//array from String [ 'a', 'b', 'c' ]console.log('array from Set', Array.from(newSet(['abc', 'def'])))//array from Set [ 'abc', 'def' ]console.log('array from Ma...
In the splice() method, The first argument specifies the index where you want to insert an item. The second argument (here 0) specifies the number of items to remove. The third argument specifies the element that you want to add to an array. Example 2: Add Item to Array Using for Loo...
log(typeof args) } getAge(21) A: "number" B: "array" C: "object" D: "NaN" 答案 答案: C 扩展运算符(...args)会返回实参组成的数组。而数组是对象,因此 typeof args 返回"object"。 20. 输出是什么? function getAge() { 'use strict' age = 21 console.log(age) } getAge() A...
My plan is to get something like this: [10,11,17]. They don't have to be sorted but the duplicates (in this case 11) has to be removed. Is there any fast way of doing it? Otherwise I would loop through this array now and then concat to a new array but I think there is a ...
Write a JavaScript program that accepts a number as input and inserts dashes (-) between each even number. For example if you accept 025468 the output should be 0-254-6-8. Click me to see the solution 7. Sort Array Write a JavaScript program to sort the items of an array. ...
除了Object类型之外,Array类型恐怕是js中最常用的类型了,并且随着js的发展进步,数组中提供的方法也越来越来,对数组的处理也出现了各种骚操作。 如果对js原型/原型链不了解的可以移步_深入了解javascript原型/原型链,_下面我们就来一起学习下js的数组。
console.log(a instanceof Array);//true (instanceof火眼金睛) 可以看出,constructor属性被修改之后,就无法用这个方法判断数组是数组了,除非你能保证不会发生constructor属性被改写的情况,否则用这种方法来判断数组也是不靠谱的。 4.用Object的toString方法判断 ...