if(typeof(obj)=="object"){alert("是对象")}else{alert("不是")},但是javascript对于object定义的很宽泛,很多东西javascript都会认为是object,比如Date, String, Boolean, Number, Object, Function, Array, RegExp, Error。判断是不是array,可以使用i
1、如果你只是用typeof来检查该变量,不论是array还是object,都将返回‘objec’。 此问题的一个可行的答案是是检查该变量是不是object,并且检查该变量是否有数字长度(当为空array时长度也可能为0)。 然而,参数对象【argumentsobject】(传给制定函数的所有参数),也可能会适用于上述方法,技术上来说,参数对象并不是一...
通过测试,使用如:obj instanceof Object的形式,只能是判断两种类型Object和Array,其中Boolean、Number、String可以判断,但是会返回false,如上面i和b变量;如果判断为null或者undefind会报Uncaught TypeError: Right-hand side of 'instanceof' is not an object这样的错误。 测试5: 直接通过Array.isArray(obj),javascri...
Object.prototype.toString.call( list );//输出[object Array] var str = 'str'; Object.prototype.toString.call( str );//输出[object String] var i = 1; Object.prototype.toString.call( i );//输出[object Number] var b = false; Object.prototype.toString.call( b );//输出[object Boolean]...
Vue Js Check Undefined Array,Object or Property: In Vue.js, you can check if an array or object or object property is undefined using the typeof operator.To check if an array is undefined, you can use the typeof operator to check if the variable hold
multiple ways to check boolean value exists in an array, using For loop with if block, Array some() method, Array indexOf method, Es7 Array Includes examples
// program to check if an object is an array function checkObject(arr) { // check if arr is array const result = Array.isArray(arr); if(result) { console.log(`[${arr}] is an array.`); } else { console.log(`${arr} is not an array.`); } } const array = [1, 2, 3]...
一、Array (1)语法 (2)API 二、Object (1)语法 (2)特色:属性增删 (3)特色:this (4)特色:原型继承 (5)特色:基于函数的原型继承 (6)JSON 一、Array (1)语法 // 创建数组 let arr = [1,2,3]; // 获取数组元素 console.log(arr[0]); // 输出 1 ...
Add value if not exists Loop through the array to check whether a particular username value already exists and if it does do nothing, but if it doesn’t add a new object to the array. const arr = [{ id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { id: 3,...
#Other Ways using Lodash or Underscore If you're using an external library, they also have some built-in methods too 👏 Lodash Checks if value is classified as an Array object. constarray=['🍝','🍜','🍲'];constnotArray='not array';_.isArray(array);// true_.isArray(notArray)...