lst = ["pig", "dog", "cat"]obj = {"name": "dog","age": 12,"sex": "man"}# 作用于数组print('dog' in lst) # Trueprint('apple' in lst) # False# 作用于对象print('name' in obj) # Trueprint('dog' in obj) # False 参考 js如何判断数组含有某值,in/includes/inArray/indexOf...
text.indexOf("e",5); Try it Yourself » Find the first occurrence of "a": lettext ="Hello world, welcome to the universe."; text.indexOf("a"); Try it Yourself » Description TheindexOf()method returns the position of the first occurrence of a value in a string. ...
console.log(list.indexOf('dog')); // 1 console.log(list.indexOf('apple')); // -1 1. 2. 方案三、includes 同indexOf一样,includes仅能用于字符串和数组 console.log(list.includes('dog')); // true console.log(list.includes('apple')); // false 1. 2. 方案四、自定义函数inArray 数...
=-1来判断是够包含 includes与indexOf用法相同,可以用于判断数组/字符串 array('a','b').includes('a')返回值为true array('a','b').includes('')返回值为false in 用来判断一个属性是否属于一个对象,即判断字符串是否在keys中 let arr=[“a”,“b”,“c”]; let arr2={“a”:“aaa”,“b”:...
The findIndex() method executes a function for each array element.The findIndex() method returns the index (position) of the first element that passes a test.The findIndex() method returns -1 if no match is found. The findIndex() method does not execute the function for empty array ...
Object inherits the hasOwnProperty method. This method can be used to determine whether an object has the specified property as a direct property of that object; unlike the in operator, this method does not check down the object's prototype chain ...
问如何在js中的for of循环中使用.indexOfEN发布者：全栈程序员栈长，转载请注明出处：https://javafor...
Array.prototype.indexOf() arrayLikeconsole.log(Array.prototype.indexOf.call(arrayLike,2));// 0console.log(Array.prototype.indexOf.call(arrayLike,5));// -1 Specification ECMAScript® 2026 Language Specification #sec-array.prototype.indexof...
[Microsoft.JScript.JSFunction(Microsoft.JScript.JSFunctionAttributeEnum.HasThisObject, Microsoft.JScript.JSBuiltin.String_indexOf)] public static int indexOf(object thisob, object searchString, double position); Parameters thisob Object The object that this method is acting upon. searchString Object...
问题:indexOf method in an object array? 一个叫Antonio Laguna的老兄问了这个问题,原文大意如下: What's the best method to get the index of an array which contains objects? 获得数组里某一个对象的索引的最佳方法是什么呢? Imagine this scenario: 比如如下场景: var hello = { hello: 'world', foo...