方法1:arr.indexOf(element):判断数组中是否存在某个值,如果存在,则返回数组元素的下标(第一个元素),否则返回-1;
let fruits = ["Banana", "Orange", "Apple", "Mango"]let a = fruits.indexOf("Apple")console.log(a) // 2
方法2:array.includes(searcElement[,fromIndex]):判断数组中是否存在某个值,如果存在返回true,否则返回false
let fruits = ["Banana", "Orange", "Apple", "Mango"]if(fruits.includes("Apple")){console.log("存在")}else {console.log("不存在")}
方法3:arr.find(callback[,thisArg]):返回数组中满足条件的第一个元素的值,如果没有,返回undefined;
let fruits = ["Banana", "Orange", "Apple", "Mango"]let result = fruits.find(item =>{return item == "Apple"})console.log(result) // Apple
方法4:array.findIndex(callback[,thisArg]):返回数组中满足条件的第一个元素的下标,如果没有找到,返回-1;
let fruits = ["Banana", "Orange", "Apple", "Mango"]let result = fruits.findIndex(item =>{return item == "Apple"})console.log(result) // 2
方法5:for():遍历数组,然后 if 判断;
let fruits = ["Banana", "Orange", "Apple", "Mango"]for(v of fruits){if(v == "Apple"){console.log("包含该元素")}}
方法6:forEach
et fruits = ["Banana", "Orange", "Apple", "Mango"]fruits.forEach((v)=>{if(v == "Apple"){console.log("包含该元素")}})
String对象的方法
方法一:indexOf() (推荐)
var str = "123";console.log(str.indexOf("3") != -1);//true
方法二:search()
var str = "123";console.log(str.search("3") != -1);//true
方法三:match()
var str = "abcd";var reg = RegExp(/c/);if(str.match(reg)){//包含}