2, 3, 4, 5]单击按钮,检查数组是否存在且不为空检查数组数组emptyArray是否为空或存在:数组nonExistantArray是否为空或存在:数组fineArray是否为空或存在:functioncheckArray
constiframe=document.createElement("iframe");document.body.appendChild(iframe);constxArray=window.frames[window.frames.length-1].Array;constarr=newxArray(1,2,3);// [1, 2, 3]// 正确检查 ArrayArray.isArray(arr);// true// arr 的原型是 xArray.prototype,它是一个不同于 Array.prototype 的对象...
换而言之,对于Array来说,如果一个对象有splice和join属性,那它就是一个Array: functionisArray(o) { returno!=null&&typeofo===‘object’&& 'splice'ino&&'join'ino; } 显然,鸭子检测很容易误把自造的天鹅也当成鸭子: alert(isArray({'splice':'','join':''}));//true 注:buck typing并不关注于类...
goodEmptyCheck(newArray());//false?goodEmptyCheck(newRegExp());//false?goodEmptyCheck(newFunction());//false?goodEmptyCheck(newDate());//false?这样一来，避免了其他情况的影响 其他特殊值的判断，null,undefined当碰到null,undefined时，会抛出错误 //TypeError:Cannotcovertundefinedornullot...
constarray=['🍝','🍜','🍲'];constnotArray='not array';_.isArray(array);// true_.isArray(notArray);// false Yes, the syntax is the same as Lodash 🤓 #Why can't we usetypeof? Often, we want to check the type of a value, we simply usetypeof ...
B: "array" C: "object" D: "NaN" 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: 21 B: undefined C: ReferenceError D: TypeError 答案:...
Cycles the carousel to a particular frame (0 based, similar to an array). .carousel('prev') Cycles to the previous item. .carousel('next') Cycles to the next item. Events Bootstrap's carousel class exposes two events for hooking into carousel functionality. Both events have the following ...
//code to check if a value exists in an array using includes function array.includes('hello'); // true array.includes(300); // true array.includes(0); // true array.includes(undefined); // true array.includes(null); // true array.includes(symbol); // true ...
Cycles the carousel to a particular frame (0 based, similar to an array). .carousel('prev') Cycles to the previous item. .carousel('next') Cycles to the next item. Events Bootstrap's carousel class exposes two events for hooking into carousel functionality. Both events have the following ...
数组fineArray是否为空或存在: function checkArray() { let emptyArray = []; let nonExistantArray = undefined; let fineArray = [1, 2, 3, 4, 5]; if(Array.isArray(emptyArray) && emptyArray.length) output = true; else output = false; document.querySelector('.output-empty...